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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.

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Old 08-30-2012, 08:12 PM
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Mike and dkirk thank you for the guidance! I'm going to be doing some work on the old girl tomorrow. Pictures to follow!
Old 08-30-2012, 09:32 PM
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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.
Old 08-31-2012, 02:48 PM
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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.
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Old 08-31-2012, 10:35 PM
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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






And here is our offending pin.



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.
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Old 09-03-2012, 09:56 AM
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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.
Old 09-03-2012, 11:01 AM
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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.
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Old 09-03-2012, 12:01 PM
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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!






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.

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Old 09-05-2012, 04:49 PM
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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.
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Old 09-05-2012, 05:05 PM
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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
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Old 09-06-2012, 09:29 AM
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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.
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Old 09-06-2012, 12:17 PM
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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.
Old 09-06-2012, 08:07 PM
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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!
Old 09-06-2012, 09:12 PM
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Sean, good luck with the fix...and again, sorry for the scare.
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Old 09-07-2012, 11:47 AM
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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.



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....)
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Old 09-07-2012, 12:07 PM
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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.
Old 09-07-2012, 03:23 PM
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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.
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Old 09-07-2012, 07:30 PM
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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!
Old 09-07-2012, 07:56 PM
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Quote:
Originally Posted by Alan Goettel View Post
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!

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Old 09-07-2012, 09:17 PM
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