[Charles Geer]

I have a stock pca clubrace car. All parts are stock with the exception of suspension and exhaust. At my last race in Atlanta a few weeks ago I noticed a noisy loose chain sound coming from the variocam area. We recently changed the

plastic pad guides on the variocam and the cam sprockets checked out fine. The car has 67,000 miles on it.



Is there a chance that my Oil Pressure Fed tensioner on the variocam is going bad. It appears to tension fine once the car is revving above 1500 RPM. Below 1500 RPM makes the variocam noisy...But only when the engine is Hot (Running for more than 10 minutes). I can't say I have ever heard anyone else having this sort of variocam problem.



Thanks, Charles

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[Greimann]

Ohh, there is a very good possibility that your oil pickup tube in the oil pan is cracked. There has been several well documeted cases that have had these symptoms.

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[rustech]

Second that. I believe there was a recent case of this exact incident on the 968.net. When the pump can't feed proper pressure due to the pickup tube crack (most often caused from lower balance shaft being off), the variocam tensioner doesn't keep the variocam chain tight enough. Results in what you are describing. You have to drop the oil pan (and remove cross member) to check. Have you checked you oil gauge to see if it reflects this condition?

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[Charles Geer]

We recently changed the Oil Pan Gasket, and were unsuccessful at dropping the entire oil pan due to the fact that we could not wiggle the oil pan around the pick up tube. We may have damaged this tube trying to wiggle it off. We would have never have guessed this is the problem.



Did the other 968 owners experience expeirience these problems at the RPM ranges I mentioned?

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[Charles Geer]

[quote name='rustech' date='Apr 27 2005, 09:41 PM']Second that.  I believe there was a recent case of this exact incident on the 968.net.  When the pump can't feed proper pressure due to the pickup tube crack (most often caused from lower balance shaft being off), the variocam tensioner doesn't keep the variocam chain tight enough.  Results in what you are describing.  You have to drop the oil pan (and remove cross member) to check.  Have you checked you oil gauge to see if it reflects this condition?

[right][post="3875"]<{POST_SNAPBACK}>[/post][/right][/quote]

Can you describe how the bance shaft can be off.

The Oil Pressure tends to drop a bit as I run the car hard around the track.

Oil pressure starts out fine when the engine is cold. But it certainly drops a bit once it get hot.

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[flash]

oof - that is a typical symptom of a worn bottom end - when you had the pan off, did you check the gaps on your bearings?

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[Eric_K]

Hi Charles -



The oil pickup sounds like a likely candidate especially if it has recently been messed with. Its also possible for the J tube feeding the tensioner to crack. I think these are more likely than the tensioner itself failing.



The reference to the balance shaft being off is that if the balance shafts are not properly aligned in relation to the crank then there can be vibration which could lead to cracked pickup tubes. There are notches in the balance shaft pulleys which line up with marks on the rear timing cover when the engine is at TDC.



I wouldn't take it on the track with the symptoms you describe. You could easily lose a rod bearing and the engine if the oil pressure is not sufficient. Not to mention the possibility of damaging the cams with a floppy chain.



Good luck,

Eric

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[rustech]

[quote name='Charles Geer' date='Apr 28 2005, 05:06 AM']We recently changed the Oil Pan Gasket, and were unsuccessful at dropping the entire oil pan due to the fact that we could not wiggle the oil pan around the pick up tube. We may have damaged this tube trying to wiggle it off. We would have never have guessed this is the problem. 



    Did the other 968 owners experience expeirience these problems at the RPM ranges I mentioned?

[right][post="3879"]<{POST_SNAPBACK}>[/post][/right][/quote]



I don't recall whether others had the same issue at lower RPMs. With the crack in the pickup tube, you can't supply enough oil/pressure to the tensioner because you are sucking up air in the side of the pickup tube.

Can you describe how the bance shaft can be off.

Since you stated you tried to get the oil pan off, you most likely damaged it then. However, it is well known that if the balance shaft belt is not properly tensioned (loose) that the shafts can skip teeth on the belts. When engine is at TDC (top dead center) the balance pulleys need to be lined up with their timing marks as well.

The Oil Pressure tends to drop a bit as I run the car hard around the track.

Maintaining oil pressure during excessive G's is already a concern for those that track their car. With a crack in the pickup tube, this problem would only be magnified.

Oil pressure starts out fine when the engine is cold. But it certainly drops a bit once it get hot.

Cold should be 4-5 bar. Idle Hot should be 2-3 bar. Working hot engine should be 4-5 bar.

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[Eric_K]

when you had the pan off, did you check the gaps on your bearings?

He said they couldn't get the pan off because of the pickup tube. I don't think they got that far into the engine. BTW, there is a sensor on the side of the oil pan (I forget what it is right now) but it has to be removed before the oil pan can be removed as it will interfere with the oil pickup when you try to remove the pan.

If you are going to check the bearings, you should just change them. At least the rod bearings.



Eric

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[rustech]

[quote name='Eric_K' date='Apr 28 2005, 07:51 AM']He said they couldn't get the pan off because of the pickup tube. I don't think they got that far into the engine. BTW, there is a sensor on the side of the oil pan (I forget what it is right now) but it has to be removed before the oil pan can be removed as it will interfere with the oil pickup when you try to remove the pan.

If you are going to check the bearings, you should just change them. At least the rod bearings.



Eric

[right][post="3887"]<{POST_SNAPBACK}>[/post][/right][/quote]



Level sensor.

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[Charles Geer]

1) I the J Tube on the Variocam replaceable?



2) My Oil pressure once the Oil is hot drops just abit.

When cold the Oil pressure idles at 3.5 and with revs goes up to 5.

When hot the Oil pressure idles at 3 and revs up to 4.5 - 4.8 under

full throttle.



3) I will check with my mechanic to make sure the engine was TDC.





4) We replace the motor mounts right before the race for the exhaust side mount

was totally severed with the engine on that side moving freely. Needless to

say the engine has had it's share of vibration problems.



5) Based on the fact that we have maintained oil pressure under throttle above

4.0 bar do you guys recommend a rod bearing change as well?

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[flash]

no - your pressure sounds pretty normal - when you said it dropped, i thought you meant below what is specified in the manual

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[Eric_K]

1) I the J Tube on the Variocam replaceable?

Yes, it is a seperate piece.



Your oil pressure is running a little lower than mine but not bad. But, is the pressure running lower than normal after this problem developed? The bearings should be ok if the pressure was always there.



I'm betting something has wiggled loose or cracked. I would check the oil pickup tube especially if it was being yanked on.



Eric

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[Vedder]

Hold ON!!!!! At cold the oil pressure in my car is 4.5, but whens hot its little lower than 2 , is this good??? At Idle of course.

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[flash]

nope - that's a bit low - what oil are you running? how long since the last change?

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[Charles Geer]

My oil pressure has remained consistent over the time that I have owned the car since June 2004.



The car has 4 De's

4 PCA Clubraces

8 Total Events on the Engine



Car was babied before June 2004



The car has not not had an additional drop since we tried to wiggle the oil pan off of the Oil pan pick up. Please note that we wiggled the oil pan for 30 minutes. It appeared to be hung up on the Oil pan pick up which we could not see.

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[rustech]

[quote name='Vedder' date='Apr 28 2005, 11:10 AM']Hold ON!!!!! At cold the oil pressure in my car is 4.5, but whens hot its little lower than 2 , is this good??? At Idle of course.

[right][post="3897"]<{POST_SNAPBACK}>[/post][/right][/quote]

Vedder, you're well within spec. Your numbers are the same as mine.



Charles, I think you know what you have to check.

(also, your cold idle you stated 3.5, it should be 4-5.) Other than that, your numbers look normal. If you are running a thinner oil, it could explain this.)

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[Eric_K]

Please note that we wiggled the oil pan for 30 minutes. It appeared to be hung up on the Oil pan pick up which we could not see.

Was the oil level sensor (thanks rustech) removed before you tried to remove the pan? I fought the same thing on my parts car engine until it dawned on me. The sensor is about 4 inches long and will hang on the pickup tube if it is not removed first. IIRC, from the outside of the pan it looks like a triangular plug held on by several small bolts.



Eric

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[Eric_K]

FWIW, my engine idles at 5 cold and ~3.5 hot with 0W-30R Mobil1.



Eric

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[flash]

while the spec calls for a minimum of 0.6 to 0.8 bar at idle, and 3.0 bar at 3k, i've not yet seen an engine with that low pressure without low compression too - what is it at 3k?



oil pressure is largely a function of clearnaces in the bearings and pump - larger or worn clearances equate to lower pressures - just under 2 bar at idle hot is not really anything to be worried about, but it is a touch on the lower side, and indicates some wear, and certainly less lubrication - as eric says too, thinner oil can contribute to this



in a street car, i wouldn't be worried about it - in a race car, i would have already yanked the motor - lubrication is the single most important thing in a race engine - there is really no room for a judgement call there - dry spinning a bearing can be very expensive



i think i'd take a look at the oil, change it if it's been over 5000 miles or over 8 hrs of track time, and install the heaviest oil i could find in a synthetic and see where it goes from there



if this is a track car, and if there is no change, then i'd take a look at guaging the bearings

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