Valve seal replacement while in car?? what is needed?

[x98boardwell]

The car is a 550 Spyder so a ton of room around the motor. The motor is a 2.4 liter twin plugged six cylinder.

How would you depress the springs? What tools are used? Trying to do this without a motor drop if possible.

Thanks,
Bryan

[lindy 911]

It is possible to do in the car but not easy. There are fixtures that bolt to the cam carrier that can compress the valve spring so you can get the retainers out and access the seal. If the seals are bad there's a good chance the guides are bad too.

An engine drop is an hour and a half max and the same to put it back. You'll spend that on one cylinder with the engine in the car I'll bet.

You mind me asking why you think you need to replace the seals? Does it smoke? If so when and what color?

[x98boardwell]

Blue smoke on WOT at higher RPM's. Compression test was 185, 185, 175, 185, 190, 185, have not done leak down. motor runs like a top. Carbs freshly rebuilt. Here is a pic.

[cgarr]

Do you know what seals are in there now?

[BoxxerSix]

Can be done in car yes, but IS a royal PITA. Far better to remove the engine. You still need the same tools regardless:

-Need basic hand tools
-Need a proper valve spring compressor
-Small magnetic-tip tool helps to pull the valve locks out w/o dropping them
-Small pick and some white lithium grease helps to get them back in
-Valve stem seal puller pliers are a bonus if you can get them(Schley sch92350)
-And most important a compression adaptor to apply compressed air to the cylinder through the spark plug hole(piston at BDC!!!!!) Keeps the valves closed.


hit enter too early.....

Reason why it's such a pain in the car is because you have to remove all the rockers/shafts to do this. Believe me I've tried, and will never try it that way again!

[x98boardwell]

Not sure what seals are in the car now. Thx for the advice... removal seems like it has to happen... if I want this to be a super clean runner.

Waiting to hear what the blue means at WOT from lindy 911 as well.... don't know what my signs mean.

Thx,
Bryan

[BoxxerSix]

Blue smoke at WOT usually indicates worn rings, but is not always the case. blue smoke under engine decel usually leans towards bad valve seals and/or worn guides, but again is not always the case. There are things that can swing that either way but in the majority of the cases that's what you find.

Certainly should do a comp test and leakdown test on the motor to at least get a little bit of information on it if you're concerned with its health.

[lindy 911]

Just guessing here but by the looks of your car it does not have many miles on the engine. I would put some spirited miles on it before any engine work other than maintenance items. It will sometimes take some time to clear all the oil from the combustion chamber if the engine has been sitting. Oil will naturally leak by the rings and into the combustion chambers even on new engines. Some here call it an "Italian Tune Up" which is essentially driving it hard for 50-100 miles to makes sure you get things good and hot and burn all the crud.

I'm not an expert on leak down numbers but I don't see anything glaring. I know the carbs are right because of who rebuilt them. Take that beautiful car out and run it like race horse. I think you'll be pleasantly surprised by the results.

[x98boardwell]

Thanks guys, will do.

Adam, I did perform a compression test.. the numbers are in my above reply with the photo... everything was good there.

Let me know if you have any other ideas.

Bryan

[CaptainCalf]

Bryan, that car is sweet! I remember seeing your old 930 before you sold it and it was amazing too. You have a knack for finding and restoring some very nice autos.

I think Lindy911 has it pegged. Even if just one of the oil ring's gap is turned down instead of up, which is easy to do while building it up if you're not careful, would allow oil to seep into the combustion chamber when it sits.

Also, I know you did your homework before buying this one, so I have to ask: if a fellow who couldn't afford an original was wanting to build one of these spyders up from a replica body kit which one would you recommend.

Thanks,
RC

[x98boardwell]

RC, thanks for the kind words. I actually drove the car last weekend about 70 miles and it didn't smoke that much. After I changed the fuel pump (old one was delivering less than 2 psi) I haven't drove it other than a start to do the compression test and to run the fuel out of the carbs... for test of course. The numbers looked good above from that stand point.

Back to trip... I drove it for about 70 miles and it barely smoked even at WOT.. heck maybe not at all. The previous problem of my carbs where I had the entire fuel for one bank running down the wall of cylinder #4 so I was washing out my cylinders and I had fuel in the oil.. It was milky and smelled like gas. Fast forward to today, new oil, rebuilt carbs, compression test done, etc. etc... I think the car is getting better. You guys may me right about just driving. I plan on doing one more oil change to get whatever residual oil/gas mixture was in the car that i couldn't get from the cooler, lines, etc.

The problems that are still apparant,
- hard start (both cold and hot).. this may change a little now that my fuel pressure is good but not sure.
- smoke occasionally... maybe this one will fix itself
- a little play in the steering.. I am addressing this now. It has a late Beetle front end (twin torsion bar setup) with CCN or CNC disc brake conversion. Not sure on the correct letters.


Other than that, this thing goes like a raped ape. We are guessing 215hp or more and it weighs 1,400 lbs... You do the math. The only thing I will do is put a LSD in the 901 trans.

You can purchase a kit used from someone with a 4 cylinder for $20,000... may not be the best built but would be fun. There are many to choose from or at least a enough to get a good one. If you want a 6-cylinder, well that is an entirely different story as they are rare and the chassis is completely different so if you wanted a 6 you would have to start with that or buy one mostly completed like I did. The PO had well over 70k into this car but he also paid someone to do a lot of the work which cost more.

Here are a couple pic's of my 3 past rides for old time sake.

[CaptainCalf]

Thanks Bryan & I know you'll get that 550 sorted soon just like you did all the others

[x98boardwell]

Well, it still smokes...

Compression and leakdown numbers.

#1 185, 10%
#2 185, 4%
#3 180, 4%
#4 190, 3%
#5 185, 4%
#6 185, 3%

It has to be the valve guide seals correct as these numbers eliminate all other options... right?

Trying to get to the bottom of this one. The motor is very accessible but also easy to remove. How big of a job is it to change the seals...? The smoke is annoying and my clothes smell after awhile. It does almost disappear but comes back on WOT and sometimes at idle.



Thanks,
Bryan

PS, I included some pics to show how accessible the motor is... but I am guessing it would still be a pain in the ass to do while in the car.

[BoxxerSix]

You're best bet is to pull the motor and put in a stand. You have to pull the rocker shafts to get the rockers out in order to even get to the springs properly. Going to have to time the cams at that point. You'd spend far too much time (IMO) dicking around trying to do the job right, working around everything in the limited space, than it would take to pull the motor out and do it out in the open.

Could it be done in the car....I cannot honestly say as I haven't seen it up close. But I'd feel comfortable saying that you probably couldn't pay me enough to attempt the job in-car.

Can walk you right though the whole thing once the motor is out though


I take that back, mid engine. May be able to pull the shafts out and drop the rockers rear-front w/o having to mess cam timing by pulling each rocker out on the base circle of it's respectful cam lobe(loosen valve adjuster completely). Yeah I take it all back....try it in the car. Worse case, you've got to pull it out.

[lindy 911]

You'll need a fixture to hold a spring compressor. You'll also need a connector so you can put compressed air into the cylinder through the spark plug hole. I think with the space you have it's doable in the car. I would do one cylinder at a time moving form intake to exhaust. I think I would remove the rocker, pressure up the cylinder to keep the valve in place, compress the spring and remove the keepers. Once the springs and retainers are out of the way, prying off and replacing the seal is a no brainer. Reassemble and then move to the exhaust of the same cylinder.

Just a thought though, we used to leave the stem seal off supercharged big block offshore race engines to help cool the stem and lube the guide. These engines NEVER smoked, not even at idle. I don't think stem seals will smoke like your talking especially at WOT.

How is your exhaust configured? Do you have two separate headers and mufflers or a common muffler? If you have a common muffler you could remove it and see if the smoke is coming from one side of the engine or the other.

Your leak down numbers indicate that the valves are seating and the compression rings are doing their job. It tells you nothing about the condition of the oil scraper ring that could be the problem. I would guess that one of the oil rings is the problem if you took the car out and ran it HARD for at least 50 miles.

[HawgRyder]

If you don't have access to a compressor....you can use the old sash cord trick.
Remove the plugs....feed sash cord into the hole....rotate the crank until the piston comes up and compresses the sash cord against the valves....then remove the locks and continue with the repair.
Bob

[WERK I]

Originally Posted by x98boardwell

Blue smoke on WOT at higher RPM's. Compression test was 185, 185, 175, 185, 190, 185, have not done leak down. motor runs like a top. Carbs freshly rebuilt. Here is a pic.

Bryan,
Beautiful car. Have you ruled out a buildup of crankcase pressure at high RPM's? Hate to see a tear down of any sort before ruling out any of the other possibilities. I see the engine is a hybrid of sorts with its own custom sump and vent system which could be a source of the problem.

Excessive pressure in the crankcase could also be gases escaping around the rings at high RPM's, leaving too much oil on the cylinder walls. I would think if you have leaking seals/guides, you would have oil smoke at engine start up as well.

[cstreit]

I don't see how the higher leakdown in #1 means only seals. It could be rings.... When you did the leakdown, did you do the "rubber glove test" to see if the air was coming from the case, exhaust, or elsewhere?

Many other things could cause this, a ring that rotated incorrectly, blowby from the rings, oil level too high(!), etc..

Hell, my 911 would ONLY do this at Road America because at the long sustained high RPM's the amount of oil that came out of the breather was tremendous.,... Like a quart per day which is more than an entire seasons worth at any other track.

[x98boardwell]

Wouldn't the compression test revealed if it were rings???

I didn't do the glove test on cylinder #1. I can do the leak down again to see where it was coming from but because it has an open exhaust, carbs and a breather tube on the oil can you can tell where the air is coming from... We didn't do it (listen) on cylinder #1 or any other cylinder because all of the numbers were acceptable.... this is why we think it's the valve seals.

Not so say that there isn't too much oil. I had 7 quarts in there before and it smoked more... at least from what I could tell. I took out a quart and it did lessen the smoke. (Note, when I change the oil I drain the tank and the case so their is still about a quart in the car... I am guessing here).

What is the oil capacity of a 2.4 liter motor or a 1973 911? This could shed some light but I think the seals may be the culprit or possibly a ring that "acts up" sometimes... if that could be.

Thoughts? Thanks for the input,
Bryan

[CaptainCalf]

Bryan, the oil scrapper ring is for just pulling oil back down the cylinder wall and the 2 compresssion rings hold the compression, so the compression test won't tell you if the oil rings are bad or in the wrong orientation.

You may be able to pull the plugs after it sits for a week and run a long q-tip in the cylinders to find out if oil is getting past the oil rings and or not.

Good luck man!
RC