4Agte Filling Catch Can Intermittently.

[kickn5k]

I recently built a 4AGTE engine for a mates sev track car. It makes good power(304rwkw @ 32psi) but has been putting a fair amount of oil into the catch can(1.5ltr over 6 laps winton).

Now this only happens when we race it, it won't do it on the dyno or when he's road driving.

The motor consists of everything brand new, rods custom pistons, huge cams, reco'd cylinder head etc.

We've changed catch can pickup points 3 times with no luck. Oil pressure isn't excessive but we have the restricted oil feed for the BB turbo other than that oil system is STD.

 

Anyone have any thoughts? Never had this much of an issue with any of the countless other engines I've built :(.

[oldie]

something to do with surge maybe as it only happens when the car is thrown around the track,not on the road or during static testing but actually why, I couldnt guess.

[Trev]

It won't be surge or anything like that, it will most likely be from when you back it off into the corners, where have you got the can lines running to?

[kickn5k]

It won't be surge or anything like that, it will most likely be from when you back it off into the corners, where have you got the can lines running to?

 

Had the can lines going to the back of the rocker covers to the can to start with. Then changed it to the front at the top. We now have them going from the factory location to the cans and it still does it.

Probably should mention it does it at the drag strip too.

The only thing we haven't done yet is a leak down test. He'll do that Tuesday.

Oil pressure at operating temp is 40psi at idle and 70-75 when it revs, which I don't think is excessive.

Thanks for the input guys, it's very appreciated!!

Edited June 2, 2012 by kickn5k

[Trev]

So is it a vented catch can or vacuum?

[kickn5k]

Yeah just vented one with a filter on top.

[ke70dave]

the smallport 4age has an additional oil drain in the head, which i assume is to help and stop the oil pooling in the head.

 

you don't say which engien you have (bigport or small), but perhaps you should put an external oil drain directly into the sump? if it is a bigport head.

 

or just put a drain on the bottom of your catch can into the sump?

[Trev]

the smallport 4age has an additional oil drain in the head, which i assume is to help and stop the oil pooling in the head.

 

you don't say which engien you have (bigport or small), but perhaps you should put an external oil drain directly into the sump? if it is a bigport head.

 

or just put a drain on the bottom of your catch can into the sump?

 

My thoughts exactly Dave but was going to wait until he checked out the engine before masking any issue it may have.

[kickn5k]

the smallport 4age has an additional oil drain in the head, which i assume is to help and stop the oil pooling in the head.

 

you don't say which engien you have (bigport or small), but perhaps you should put an external oil drain directly into the sump? if it is a bigport head.

 

or just put a drain on the bottom of your catch can into the sump?

 

Sorry it started life as a late smallport 4AGZE, then when the arp head stud restricted oil to the camshafts the head went in the bin and a bigport was used to replace it.

Doing a leak down test Tuesday night so that will confirm if it's a ring seal issue.

[TRD ke70]

I meant to reply to my post the other day concerning this, as you know we had been struggling with the same problem.

We have been through all the catch can ideas, as well as venting from the left rocker cover, after a bit of pissing around we removed the center bung on the head and rev'd the engine to over 6500rpm, found that the oil level in the head drastictally increased once over 6500, this led me to think oil pressure.

We had increase the pressure relieve valve tension, this was not the way to go. At 6500rpm oil pressure was over 90 PSI and i'd be guessing oil volume to the head would have increased as well. Coupled to this we have a brand new crank and brg's, so it's pressure would have been high already.

Try it and see if you have the same problem, we think we have fixed ours by reducing the pressure relief back to standard.

Because the oil pump is driven off the crank, there's no need to increase the pressure relief.

Let us know what you find, it appears to be a common problem on highly tuned 4AG's.

[kickn5k]

Thanks for everyone's replies!!

TRDKE70, the oil system other than the catch can setup and the little restricter in the feed line for the turbo is STD. But I still think I need to check oil pressure in the highend rpm myself once it's checked put back together.

Trev and Dave. I think this is also what might be causing some if not all of the issues. When the motor was STD GZE and the first motor built. It had the smallport head and the drainback. Now we've gone to the bigport it doesn't have a drain and this is exactly when these problems started.

Might have to look at a drain at the head after everything is checked.

Thanks everyone again. I'll post up the solution to the problem when we get it done.

Edited June 3, 2012 by kickn5k

[kickn5k]

Ok I have some findings.

Leak down test proved inconclusive. 3.5-4% I would have preferred a little less but considering the ring gaps we had to work with that shouldn't be too bad. It also has the smallport GZE drain put into the bigport head.

Now having a chat to a customer of works(I'm lucky working were I do, the contacts you end with are very handy) he has played with 4a's for years. He explained a few things that fixed the same issues with some of his cars so well try that and report back soon. It sort of comes down to RWD'ing a FWD engine when it's being asked a lot more than STD. I'm not keen on saying what he told me until I know it works or it don't.

[TRD ke70]

I meant to say, ours is a smallport head with the drain in the back of the head.

Good luck, hope you fix it, as i know how much of a pain it is.