Epoxy... Really??
 

Hi folks!
I can honestly say this is the one pelican forum that I never thought that I would be posting in...

Here is my dilemma. After melting the engine harness in my 87 930 I decided to take the time to diagnose and rectify some oil leaks that have been troubling me for some time. I am planning on replacing the crank breather gasket, thermostat o-ring, oil pressure switch, the distributor o-ring, the oil cooler seals, oil cooler hoses, valve cover gaskets, and contemplating the pulley seal and intermediate shaft seal, when I found this:

http://forums.pelicanparts.com/uploa...1346103172.jpg
http://forums.pelicanparts.com/uploa...1346103187.jpg

This blob of epoxy is just behind the #4 cylinder on the passenger side cam box.

I am assuming that I need to do a partial engine drop, pull the cam covers and inspect the inside of the box(s)?

What is the deal with the epoxy? normal? Covering a larger issue?

I also guess I should be adding cam cover gaskets to my ever growing Pelican shopping list as well as the pulley seal, and intermediate shaft seal (I am having a hard time locating a part number for this one).

Any thoughts and information would be welcomed and appreciated!

Best,

It's standard to have epoxy on the pin bosses. It is used to keep the area fluid tight. Clean the area of all epoxy and re-apply.

The pins have been known to walk out when the bores relax from age and stress. This is usually more of an issue with magnesium boxes.

So if the pin has indeed walked. To rectify I need to open the box re-insert the pin and then re-epoxy? Problem solved - best case?

The oil leak does imply a loosening on the bore, which may be brought on by non bushed arm binding. I would Inspect the arms IF they are not the updated wide and bushed arms. If they are the wide arms, then simply clean, inspect for cracks, and re-apply the epoxy.

Thank you for the tips! I will report once I open the box up.

Taking a look at things inside the chain housing won't hurt.

But you could just re-epoxy after careful cleaning and leave it at that. Engine builders often do that with all rebuilds whether leaking or not. Can't expect the epoxy to stand all that heat forever.

If something has gotten loose, the new epoxy will fairly quickly crack and leak again, and more heroic measures can be undertaken.

If this is the pin I think it is, it is also captured, though not as tightly, in the chain housing cover at its other end. Since it is supported on both ends, it isn't going to cause catastrophic failure if it moves a little.

Well I am at a point now where I feel it wise to break into the chain box and fix whatever has happened in there.
It all started with a burned engine wire harness and after removing the CIS and Intake manifold I decided that I may as well chase some oil leaks that have been pestering me for quite some time.
Also I am pulling the HVAC out of the old girl since... well, it has never been that stellar and I am in California.
So here I am with the exhaust off the top of the motor removed and getting ready to delve into gasket replacement when I found this hole. Jeesh... no time like the present!
I am hoping to do this with a partial engine drop, as I don't have space in the garage for the engine and the cars.
I guess the new question is this:
Can I simply remove the cover, re-insert the pin, re-epoxy, instal the new gasket, and button it all back up? Or will this be WAY more involved?
Thanks for the help and insight!
Best,

Sean,

The pin is for the tensioner arm. To do any work will require removal of the arm and risk needing to re-time the cam.

It may be wiser to simply put epoxy on it and inspect/fix it when you need a valve job or something.

Exhaust on top of the motor? Sounds like you've got more problems than just a leaky chain tensioner post....... ;)

Both top and bottom are removed.

LOL how punctuation can kill us some times!

Looks like you are already in pretty deep. How are the cam gaskets and orings? Dry? If not, you might want to consider replacing them while you are so close. Yes, it will involve re-doing the cam timing, and yes, you can do it in the car.

I will have to research about resetting the timing... I did plan on replacing the gaskets, but I had not considered the o-rings as of yet. I honestly figure that while I am this far into things I may as well do everything I can to stop any possible leaks... welcome to the slippery slope eh?

BTDT! :) Have fun. Do it once and do it right!

You keep thinking you will have to, and can simply, reinsert the offending pin.

I repeat - I'm not sure it came loose, at least not so loose that when you remove the chain tensioners and then the idler gear arm, you can pull the pin out with your fingers. Though if you can, that is something good to know, although it means a lot more work.

The pin is a press fit, and I don't think it is available as a replacement part, as it is intended to be integral to the chain housing. From reading posts here (you ought to do a search to bone up on the subject), it seems that if it has really gotten loose you need to have a replacement made to be a press or heat/cold fit into a slightly enlarged hole you machine into the housing.

Which probably means removing the housing. Which is now getting to be a pretty big deal, because I don't think you can remove the housing without removing the cam - the end of the cam sticks out a fair amount, but someone can correct me on this. To remove the cam, you have to pull all the rockers. You will have to remove the chain ramp, though, in any case.

I have retimed a cam with the engine in place, but it was a race prepared 911 and I could, among other things, remove the rear crossmember with a few bolts (I had modified things), the rear bumper and valance came off with four butterfly Dzus's, and it turned out I didn't actually have to retime the cam.

Speaking of which, I did this because I had forgotten to tighten the three 10mm headed bolts holding the cam holder, with its O ring and gaskets, in place, and it leaked a lot just driving it into the trailer . Somehow the cam never moved while I removed the big nut, and the gear, and put them back on. It seems the valve springs, by pressing the cam lobes in various directions, helped hold the cam in one position. So all I actually did was recheck the timing. But checking the timing is a whole lot easier with the engine up on a stand, becaus with it in the car you can't easily see if your dial indicator is on the flat part of the valve spring retainer or not.

In your case, to get the cover off (being on the left side is a boon here) you need to pull the sheet metal, prop up the rear of the motor, and remove the motor mount and crossmember. That should give you enough room to get the cover plate off to see what is going on inside. I don't think a partial drop is going to be of enough help, and you have to do all of the above to make any use of a partial drop anyway.

As to leaks in this area, there can be leaks from the joint between the chain housing and the case. And from the O ring around the gizmo which holds the cam in place, as well as the gasket on its other end. But lots involved in getting to these as opposed to some other gaskets (like valve covers), so I'd not do this outside of a full engine rebuild. Unless I knew they were leaking enough to make the effort worthwhile. And you ought to be able to pinpoint such leaks, if they are there, the same way you did the one you wrote about - by cleaning and looking.

Mike B works doing this stuff, so his responses tend not to ramble on as mine do. But you really ought to place a lot of weight on his advice, and not let this project get out of hand: either cleaning and new epoxy will stop this leak for a reasonable amount of time until it is rebuild time, or it won't and that time is at hand. The epoxy is there to stop any oil which migrates past the press fit, which isn't going to have any significant pressure behind it. If the pin wobbles or rotates, that means the hole has enlarged, but more to the point the new epoxy will promptly crack like the old.

So if you pull the chain housing cover, you might want to have that in mind. I wish you the best of luck, as so far I have not had this problem with the various chain housings I have in my engines.

clean, re-epoxy and call it a day. save it for a full engine drop when your doing a top end.

You "can" remove the chain housing without removing the camshaft and rockers. Once you're in there that deep, its pretty easy actually.

Well, I cleared the remaining epoxy and applied a light load to the pin to see if it would move. It feels fairly secure, though there is oil seeping by...

I am at a loss! Part of me wants to break into the housing and have a look and re-press the pin properly, the other half says epoxy over the thing and see what happens.

Though I am quite relieved that it is not wobbling around in the housing.

KISS (keep it simple stupid)

Depending on your reliance on this car as a daily driver. If you are not dependent on it, I would start with just re-epoxying and seeing how it goes. You are unlikely to incur any damage to anything if it does wiggle a bit and break the new epoxy free. An oil leak in this area will be your early indicator, long before any damage is done, that you need to get in there for some serious work. Your challenge with this approach is going to be getting all of oil out of the joint before you reapply epoxy.

Well said, Mark Brown.

Sean,

For the best epoxy to be used in this application, I recommend JB Weld. Clean the aluminum several times with lacquer thinner before applying. Get the quick-set JB Weld that hardens in 3 minutes and it won't sag and run while drying. Color is grey so it looks exactly like OEM.

Mike and dkirk thank you for the guidance! I'm going to be doing some work on the old girl tomorrow. Pictures to follow!

I've used the JB quick weld for things like this before and under repeated heat cycles it shrank, warped, delaminated and then leaked. I wouldn't use it there and if you do keep an eye on it from time to time.

The regular 24 hour hardening JB weld is much better and is more stable and longer lasting for a job like this. A thick layer will run or sag under gravity but you can smear on a thin coat and then another over it after it sets up in a few hours to get some thickness.

Another real good epoxy is Devcon marine epoxy. It's actually better than JB weld it just isn't marketed much.
You can also buy it in a putty form that doesn't sag and can even be applied under water.
Marine and aviation products are usually alot better quality than generic automotive and household stuff.
Devcon Marine/Plastic Epoxy Putty S-80 (80354)

Along with cleaning the area of oil with laquer thinner or acetone I would scuff it with some 80 grit sandpaper to rough up the surface a little so the epoxy will stick better.

i've never used (nor heard of) devcon, but i've really been impressed with marine-tex. marine-tex also has a rapid set version, but i have never used it.

Alright climbed back under the old girl and did a bit of cleaning and thought that I should take a couple of images for final analysis here goes:

These are the press fit pins on the drivers side chain box, neither are leaking but both look like they could use a bit of epoxy


http://forums.pelicanparts.com/uploa...1346691100.jpg

http://forums.pelicanparts.com/uploa...1346691115.jpg

And here is our offending pin.

http://forums.pelicanparts.com/uploa...1346691338.jpg

Should I really just epoxy over this and monitor it? I feel like I should open the box and re-press it since the other pins are all flush with the box... however, I really don't know what I am doing so I am asking for the final word from those who have been there before.

The pin itself can't go anywhere. When you look at the chain housing cover plate, you see a cadmium plated plug next to where the chain tensioner oil line attaches. That plug seals the drilling in the cover plate into which the pin is inserted when you put the plate on. So the pin, which is a pivot pin for the idler wheel arm, is supported on both ends. Where the pin is laterally isn't going to matter as far as strength in bending is concerned for the pivoting process.

Doing a very crude measurement (too lazy to dig out instruments) on the motor on my engine stand, it looks like by design the pin does not go full depth into the cover plate recess. But there is nowhere nearly enough extra room for the pin to pull out of the other end - the end you are looking at.

Aaron noted that the loads which are most apt to affect this pin are rotating, which could cause the pin to turn a bit this way and back that way. Which would quickly break the epoxy seal. In your case, with some extra depth for the epoxy to fill, you might even have a better lifetime of your seal - perhaps the bond would break on the end of the pin, but not where the epoxy adheres to the housing. Pin might still rotate a little, but not leak.

If I had to guess, I'd guess your pin isn't rotating. Your turbo came with the pressure fed tensioners, did it not? In any case, its model year is several years after Porsche went to the longer bushing idler wheel carrier. Some think that this actually cured the tensioner problems, and the pressure feed system was engineers chasing a problem they had already solved. In any event, it is hard to see that the bushings, which are oiled though by gravity and dripping, are likely to stick enough to twist the pin.

I have no explanation as to how the pin seems to have moved rearward a bit. The ones I have seen are all flush, like your other ones. So I sympathize with your uncertainties. From your initial picture, it kind of looks like the epoxy never filled the hole, which suggests the pin moved. But that is placing a lot on a picture which showed the leak definitively, but wasn't quite at the microscope level of detail.

I don't know how you would press the pin back into place, assuming it has moved, with the chain housing still on the motor. Hitting it with a brass hammer comes to mind, but you'd at a minimum want to brace the area of the chain housing immediately behind the pin head. Those housings were not designed to take fore and aft loads. I suppose light tapping wouldn't hurt. But if that moved it, it is pretty loose. With some Rube Goldberg machinations you might be able to use a Porta-Power against the chassis to get some force on the pin end, but you are faced with the support issue there as well.

For that matter, a guy maybe could drill the pin from the exposed end (might take a rather special setup, as things are tight for space with everything in situ), tap the drilling, and then use a washer and bolt to draw the pin back. At which time you could loosen the bolt, apply epoxy, and tighten the bolt and washer back on, for an even better than factory oil seal. I ought to try that on mine when I have the housing off, just as a precautionary measure if I have time on my hands.

If this were mine, and I decided it needed to be fixed, I wouldn't mess with doing it with the piece in the car. I'd remove the chain housing and get it to a machinist who could remove the old, rebore the hole, machine a new pin to fit the oversized hole but have a shank of stock diameter, and press it in with his press.

As others have said, this kind of thing is most efficiently done in conjunction with, at a minimum, a top end rebuild (although at that point on a motor of this vintage, if it hasn't previously been rebuilt it makes sense to do a full teardown and replace the crank and rod bearings). That is when all the needed parts have been removed anyway.

Seems to me your choices are to epoxy and watch, or to pull the cover. At that time your choices, depending on what you find, are to epoxy and watch, or to pull the motor and remove the chain housing for pin repair.

When you pull the chain housing cover, you would want to remove the idler assembly. This would allow you to inspect its bushings, and the wear surface of the pin, to see if either (most likely both) are all messed up to the point where the idler won't pivot easily. And to press a bit on the pin to see if it moves. For that matter, you could grab its outer end with vice grips (there should be an area beyond where anything pivots) and see if you can twist it.

Aaron is the only one contributing to this discussion who I know builds engines for a living. I don't know if any of the rest of us, who I am assuming work on our own engines, have had to deal with a loose pin. The epoxy cracks after a while on most motors, but mine have never presented with the recess under the epoxy you have.

Thanks for the reply Walt, it is funny, I too thought of drilling and tapping the pin. With the new knowledge that the pin actually can not escape the box I think that I will just go the epoxy route, especially since the boxes are currently not leaking.
Thank you for your time and knowledge!

And yes you are correct in the assumption that I do indeed have pressure fed tensioners.

Hey Sean,
You are not alone. Your post and photos are infact dejavu for me!...complete with heart palpitations and cold sweat!

Similarly to you, I ventured to locate the source of a considerable puddle of oil deposited on my garage floor. This was not the usual odd drop or two over a couple of weeks, but a sizeable puddle overnight after driving the car. This phenomenon persisted for approx. 3-4 weeks before I had an opportunity to investigate.

The offending area was promptly isolated to the epoxy blob on the chain housing behind cylinder #1. Upon probing it with a screw driver, the remnant epoxy gave way together with a sizeable gulp of oil!

I was admittedly puzzled (while reality was setting in) by the complete absence of the pin. I was staring at a gaping hole in the chain housing!

http://forums.pelicanparts.com/uploa...1346886838.jpg
http://forums.pelicanparts.com/uploa...1346886919.jpg
http://forums.pelicanparts.com/uploa...1346886968.jpg


It is needless to elaborate on my visions of cam chains flapping around loose and jumping teeth, resulting in mangled valves and broken pistons. You see, I had been driving the car for the last 4 weeks, unbeknown to me, with a pending catastrophe! The only reason that this was averted, was because of my “oil leak investigation”! I still get goose bumps thinking about it.

Remarkably, my offending pin was subsequently fished out through the oil drain hole, in the bottom of the crank case! Completely unscathed!

To keep the subsequent story short; This incident was the start of my slippery slope in Feb 2010 (which btw is still in progress today). You can gather from the photos that I have opened the motor to repair it.

So Sean & Walt, I can confirm that the pins in the LHS chain housing can in fact work loose and fall into the engine. The LHS pins were not supported or constrained by the LHS chain cover.

Here is a photo (from my build) with a good view of the RHS cover. It doesn't seem that the pins are supported by this cover either.

http://forums.pelicanparts.com/uploa...1346888252.jpg

personally, i would just find another chain housing if any of the pins are loose. the housing can be removed over the cam snout, but if you have SSIs, the exchanger is in the way and needs to be dropped.

Costa P's problem is different from Sean's. Costa's problem was clearly a chain ramp post coming loose, strange as that may be. Sean's problem is definitely the chain tensioner and chain idler gear arm support post. The tensioner/idler post is definitely constrained by the chain housing cover. The chain ramp posts are not.

As long as you're already under there, it's wise to remove the chain housing cover and lean on the post a bit to see if it is indeed loose. I agree with JW that a loose post is easily fixed by a used chain housing. They're very easy to find used. Just need to ensure that your used housing is of the same "length" because sometimes when head or case work is done, the chain housing is also machined to keep the cam properly located within the chain housing

Sorry, my bad guys. I completely overlooked that subtle detail! The sight of the old epoxy and similarities to my ordeal…I inevitably jumped to conclusions! Thanks Kevin.

Costa - you had me going there for a while - did I look at the wrong pin, etc.

But good pictures, and a great story - how the heck could that happen?

I'm not too surprised that nothing worse happened before you caught it. Generally, stuff which gets loose in the case sits down in the bottom, drawn toward the screened pump area, and doesn't cause problems. Like valve lash adjusting nuts, or broken pieces of the elephant feet. Though exceptions to this might be disasterous.

And your tensioner was still keeping the vibrations down to a dull roar. And at least one pin held the ramp more or less in place.

I am surprised that you did not have a much more massive oil leak sooner. I once had a pressure tensioner fail, and replaced it at the track with a non-pressure one. This left the hole where the pressure line fits. I had a non-pressure replacement cam oil line with me, but not an old style chain housing cover. I brilliantly filled the hole with a plastic plug, which got me through the weekend.

Stupidly, I didn't bother to fix all this properly before my next track weekend, and the plastic plug rather promptly blew out. Despite the fact that none of the oil in that chain housing area is under much pressure, nor is the housing full of oil up to that level, the result was loss of a whole lot of oil and the appearance of a blown motor or the like - though of course it was not. I was impressed by the ability of the oil mist suspended under crankcase pressure to lead to the loss of an impressive amount of oil in a short time.

So I am surprised that that old epoxy over where your chain ramp pin had been didn't dump more oil out much sooner.

WOW Costa! Had me going!! I pulled am waiting for all my pelican parts to arrive and will address the pin issue with JFairman's recommendation, that said I will also be looking for a replacement chain housing on the cheap to do a more permanent fix. I'll let you know how it all turns out!

Sean, good luck with the fix...and again, sorry for the scare.

Walt, in fact the last time I drove the car was at a P.C. time trial. On my second lap, out of the blue (no pun intended) the car started spewing embarrassing amounts of smoke! This occurred within seconds after getting on boost down the straight. I immediately got off the gas and moved off the line. The engine sounded fine, idled fine and the gauges read ok (nothing unusual wrt temp & oil pressure). By now the next marshal was waving me to return to the pits. In fact the smoke stopped completely while I was coasting back to the pits.

Once back at my bay, I found considerable amounts of oil spray on the back bumper and under the tail. After a thorough visual inspection of all the usual suspects (oil lines, hoses etc) I couldn’t find anything wrong other than some fresh oil coating the exterior of the heat exchangers and exhaust.

One of our local gurus suggested that I check the engine oil level, pointing out that the combination of overfilled & cornering forces can result in oil being sucked into the inlet manifold via the breather hose (this then explaining the blue smoke). In fact he suggested that one should avoid running more than ¾ oil level on track days. (Come to think of it, I’v completely forgotten to cross check the validity of this info!) My oil dipstick read a touch above the full mark.

Somewhat comforted by this finding (and with the approval of the club’s scrutineer that my car was sound and not dumping oil) I proceeded to take the car out again on the next practice session. I cautiously completed one lap while having one beady eye on the oil pressure gauge and the other on my rear view mirror. No smoke under mild acceleration, no smoke during overrun, in fact everything appeared normal. With renewed courage, I got on the gas in 3rd gear and stretched its legs down the back straight….and within seconds of getting on boost, the embarrassing cloud of blue returned. :(

Needless to say, I returned to the pits, with my head hung in shame. After another fruitless visual inspection, I packed up my stuff and drove back home. That was the last time I saw that cloud of blue smoke.

The oil seeping past the epoxy blob, was accumulating on the heat exchangers and exhaust. Once the exhaust was hot enough, it emmited the embarrassing trail of blue.
http://forums.pelicanparts.com/uploa...1347044808.jpg
http://forums.pelicanparts.com/uploa...1347044833.jpg

Back home, I eventually traced the new puddle of oil back to the chain housing……and that moment my friends, was the start of my slippery slope! (but that story belongs in another thread....)

That's what is so great about these lists - you think you've seen a lot on your own car, and read about more, and along comes someone who had a chain ramp pin fall out into the case!

One more thing to look for when you can't figure out where oil is escaping from.

Stories like that freak me right the hell out.

FWIW, I agree regarding the superiority of slo-set JB weld vs. the qwik version. Also, the instructions for JBW do say that in warm weather it may be better to allow the mixed epoxy to sit for a while before application to avoid dripping.

It's amazing stuff- purported to be good to 600F.

It can be done.
 

But retiming the cams in the car is really a ***** even if you've done it before. If you aren't exactly sure what you are doing, it could piss off the Pope. The hardest trick was to hold/get the cam in place to push the stinkin timing pin in.

Unless it needs a valve adjustment, or the cam seals were leaking, I'd check the pin out, glue it up, fix the seals and drive it until an engine drop / winter project.

Either way, good luck!

When doing cam timing, you want to make sure the valve adjustment is perfect. (at least on cylinders 1 and 4) If not, you may as well just throw a dart and guess.
Cam timing is not that difficult if you are using the proper tools. When torqueing the cam nuts/bolts (depending on the year) think of it as an assemetric exercise. Apply equal pressure to the holding tool as the torqueing tool without moving the cam position. Again, take your time. Do it once! Do it right!