Tear down diagnosis

[assault187]

A little history of the problem

I had a reputable dsm shop assemble my rotating assembly roughly 2 years ago and the motor has burned oil since day#1. I assembled the rest of the motor and was told by the shop it may be the turbo, maybe the valve seals so I just lived with it because I was getting no where with the complaint. Over time I have swapped the head with fresh everything onto the car and 2 turbos since and still burn through oil.

Upon motor swap I burned maybe 1 quart every 2 weeks, Now I burn 1 quart in a 40-60 mile cruise... Its really getting rediculous and I have to take care of the issue. I plan on pulling the motor out of the car after the JMFabrications open house sept. 14th and wanted to know what to look for concerning the excessive oil consumption

Leak down reveals air pressure through dipstick, The compression is 170psi evenly across the cylinders with 8.5-1 compression ratio. The needle rises quickly and steadily for all 4 cylinders so this alone has me a bit puzzled. I am pretty certain that the oil consumption is from improperly gapped/misaligned piston rings but the comp test reveals differently...why? There is no other explanation, No leaks, good head, new seals, good turbo etc.

What would be your input on the situation at hand?
What should I look for when disassebling the engine?
What ring gap would be necessary for an application like mine (Holset HX-40 pro, 27-35psi w/meth, possibly higher octane, daily driven)?

I just want to know how to be positive that I have found the problem and feel confident that all is well when it goes back togather.


All bearings and seals will be replaced with new upon re-assembly, Mod list is in profile. Thanks for the help! hope this goes smooth

 

[VETTE_50_TH]

First off, the JMFAB meet is Sept 14th i thought. Secondly, do you know that the car isnt leaking oil and not burning it. My car leaks oil then burns it.

James

 

[assault187]

First off, the JMFAB meet is Sept 14th i thought. Secondly, do you know that the car isnt leaking oil and not burning it. My car leaks oil then burns it.

James

Regardless when the open house is...The motor is coming out the day after.

I am 1000% sure my car is not leaking then burning it....c-mon dude, was that a serious thought !? Read what was written above in the original post....

 

[16g-2ndgen]

1.ok if it passed the leakdown test and compression test, i doubt its the bottom end, becuase if it was, those test would have told you. does is for sure burn oil? have you pulled the plugs to see if there is oil on them? your plugs should be SOKED if your burning that much, just turn the motor over with the injectors unplugged and see what gets on the spark plugs. is your holset hx-40 good?

2.look to see if the cylinder is soaked in oil.

3. dont know off the top of my head, but im sure somebody on here can tell you the correct gap.

 

[VETTE_50_TH]

Regardless when the open house is...The motor is coming out the day after.

I am 1000% sure my car is not leaking then burning it....c-mon dude, was that a serious thought !? Read what was written above in the original post....

Actually, it was a serious thought, becuase your car has good compression and leakdown test was good. So it kinda makes sense that its not your car burning oil. Give that some thought before you bash someone trying to help you.

James

 

[assault187]

1.ok if it passed the leakdown test and compression test, i doubt its the bottom end, becuase if it was, those test would have told you. does is for sure burn oil? have you pulled the plugs to see if there is oil on them? your plugs should be SOKED if your burning that much, just turn the motor over with the injectors unplugged and see what gets on the spark plugs. is your holset hx-40 good?

2.look to see if the cylinder is soaked in oil.

3. dont know off the top of my head, but im sure somebody on here can tell you the correct gap.

Same outcome with the last 3 turbo's so that rules the turbo out and yes the plugs are normally covered in oil. Last time I pulled the head off to replace the HG there was oil on top of the pistons, Not much at all but it was still there and the problem has only gotton progressivly worse since then.

 

[assault187]

Actually, it was a serious thought, becuase your car has good compression and leakdown test was good. So it kinda makes sense that its not your car burning oil. Give that some thought before you bash someone trying to help you.

James

Where could I be leaking oil other then inside the engine where its going to burn rather then onto the manifold? I wasnt bashing you, but in the OP it states there are no leaks. Specify what scenerio you are talking about

 

[delta448]

I'm in agreement with the others, it sounds much more like you have a leak and the oil is being burned off outside the engine. The problem is really not likely to be in the bottom end.

If you pull the plugs and are convinced that the oil is being burned in the cylinders then I'd start double checking the work done on the head. Bad stem seals, lots of slop in the valve guides, a bad valve cover gasket, leaking headgasket, too high pressure to the turbo... any of those can cause oil consumption.

If the plugs are clean, then I'd start removing the downpipe and turbo and see if you spot any places where oil has been dripping (gushing?) onto a hot surface. There was a thread a few weeks ago where a guy found out his turbo oil drain line was leaking and the oil was dripping into and all the way through the flex section of the downpipe and getting burned up in his exhaust.

 

[VETTE_50_TH]

Where could I be leaking oil other then inside the engine where its going to burn rather then onto the manifold? I wasnt bashing you, but in the OP it states there are no leaks. Specify what scenerio you are talking about

Well if your turbo is good, then i would say a return line, or your front case. Have either of those been replaced? And how about the OFH, how does that look. Any signs of oil outside of the engine? Recheck your leakdown.

James

 

[VETTE_50_TH]

I'm in agreement with the others, it sounds much more like you have a leak and the oil is being burned off outside the engine. The problem is really not likely to be in the bottom end.

If you pull the plugs and are convinced that the oil is being burned in the cylinders then I'd start double checking the work done on the head. Bad stem seals, lots of slop in the valve guides, a bad valve cover gasket, leaking headgasket, too high pressure to the turbo... any of those can cause oil consumption.

If the plugs are clean, then I'd start removing the downpipe and turbo and see if you spot any places where oil has been dripping (gushing?) onto a hot surface. There was a thread a few weeks ago where a guy found out his turbo oil drain line was leaking and the oil was dripping into and all the way through the flex section of the downpipe and getting burned up in his exhaust.

I think that is what my car is doing. But i also have a lot of oil around the head and front case too. Thats why this car is scrap soon!

James

 

[assault187]

I'm in agreement with the others, it sounds much more like you have a leak and the oil is being burned off outside the engine. The problem is really not likely to be in the bottom end.

If you pull the plugs and are convinced that the oil is being burned in the cylinders then I'd start double checking the work done on the head. Bad stem seals, lots of slop in the valve guides, a bad valve cover gasket, leaking headgasket, too high pressure to the turbo... any of those can cause oil consumption.

If the plugs are clean, then I'd start removing the downpipe and turbo and see if you spot any places where oil has been dripping (gushing?) onto a hot surface. There was a thread a few weeks ago where a guy found out his turbo oil drain line was leaking and the oil was dripping into and all the way through the flex section of the downpipe and getting burned up in his exhaust.

I will take all of your guys opinions into consideration but there are no leaks anywhere on the motor. The oil fliter housing was ported to relieve excessive oil pressure, Plugs have oil on them, still burns oil with 3 different turbo's, 3 headgaskets, and you got it....3 heads, everyone of them had new seals. The latest head has brand new everything.

Installed maybe 4-5 months ago

You must be logged in to view this image or video.

I am meticulous with the car, I will notice a leak outside of the motor. The underside is just as clean

You must be logged in to view this image or video.

Onto some other input that may be of intrest...
I was PM'ed by another member on the site who had the same problem with the same scenerios who found it to be a cracked Ross pistion upon tearing the motor apart.

 

[crimsondragon]

I say bad rings. The oil is just sealing it making it look like you have good compression. Are you smoking at all?

 

[delta448]

There's only a couple things I can think of if you're certain there's no leak. One is what Tim suggested above, the other is that either the bearings, pistons or rings were improperly clearanced. If things were too tight on the bearings, you'd have seen pretty high oil pressure -but- ...you ported the oil relief. Do you know how excessive the pressure was before the porting was done? I didn't see balance shaft elimination listed in your profile, was that done or do you still have the shafts?

 

[VETTE_50_TH]

I say bad rings. The oil is just sealing it making it look like you have good compression. Are you smoking at all?

Yea, i guess I am leaning towards that right now since that car is very clean. I remember seeing at the meet. I would have to say its your clearance too loose. If it is too loose, you will still have good compression but have a greater chance of blowby.

James

 

[assault187]

There's only a couple things I can think of if you're certain there's no leak. One is what Tim suggested above, the other is that either the bearings, pistons or rings were improperly clearanced. If things were too tight on the bearings, you'd have seen pretty high oil pressure -but- ...you ported the oil relief. Do you know how excessive the pressure was before the porting was done? I didn't see balance shaft elimination listed in your profile, was that done or do you still have the shafts?

I must have missed that in my profile, but yes I did do the B/S elimination with the shaft removed. I just recently ported the oil relief and previously the oil pressure would hit 100psi by 3400-3800 rpm.

crimsondragon, It smokes after coasting fuel cut either when I stop or accelerate, smokes after stopping, when accelerating, upon start up but will not smoke after starting and letting idle. I can let it idle and rev the motor and I wont see smoke.

Vette 50 th, The case is new and same with the oil fliter housing. The return line was checked last time I pulled the turbo to disassemble and check it which was just a couple weeks ago.

 

[delta448]

The bearing clearances are too tight. There's no way you should have ever seen 100psi at 3400 rpms unless you use thick oil, it's extremely cold and right after starting the engine.

 

[assault187]

Ross pistons .020 over for 27psi+

.0055 PTW clearance
Top rings @ .019 gap
Bottom rings @ .023 gap
Mains @ .002 clearance
Rods @.002 clearance

Does this look good? These are the specs I plan on going by when I re-do everything and for reference when checking whats in there already

 

[assault187]

The bearing clearances are too tight. There's no way you should have ever seen 100psi at 3400 rpms unless you use thick oil, it's extremely cold and right after starting the engine.

I use 5w30 full synthetic, and I always let the car idle up to normal temp before driving it. Also keep in mind I am also running the forward facing oil filter housing so there is no oil pressure lost to an oil cooler or anything.

 

[delta448]

Looks okay... not so sure about the bearing clearances you listed... I'd have to look it up and I'm at work right now. I don't think I'd aim to go any tighter than 0.0015" on the mains and rods.

I'd imagine without the oil cooler that your pressure would read lower... ? Isn't the pressure taken from a point between the pump and filter?

edit: Okay, so after some searching on this site it seems that the concensus is the mains should be between 0.0008-0.0016" with a service limit of 0.0040". Here is a post from a member I consider to be reliable. The rod clearances should be between 0.0008-0.0020" with a service limit of 0.0030". I still stand by my original post above. Tighter than 0.0015 and you'll see a marked increase in oil pressure.

Disclaimer: I still have not found the numbers in the edit in a FSM yet.

 

[assault187]

I'd imagine without the oil cooler that your pressure would read lower... ? Isn't the pressure taken from a point between the pump and filter?

Well, If you think about it the oil pressure should be lower from passing through additional lengths of tubing and flowing through a cooler which will cause resistance lowering oil pressure.

So after the research we both did, The tolerances I listed should be OK just as long as I dont go tighter then .0015 on the rods and mains?

 

[delta448]

Well, If you think about it the oil pressure should be lower from passing through additional lengths of tubing and flowing through a cooler which will cause resistance lowering oil pressure.

Yes, but if the oil pressure sender (or tap, if mech. gauge) is between the pump and the cooler the resistance to flow will cause higher readings on the gauge. Without the cooler the same pressure to the mains might read lower. BTW, I don't know what the actual route is of the oil passages w.r.t. the pump, filter, cooler and sender especially on your forward facing housing, I could be completely off-base on that guess.

So after the research we both did, The tolerances I listed should be OK just as long as I dont go tighter then .0015 on the rods and mains?

That's what I'm thinking. It'd be interesting to know what the clearances are on your bearings right now. That could be the entire issue. I hope someone didn't use 7-bolt main bearings on your 6-bolt, they aren't the same from what I've heard. But I've never torn down or rebuilt a 6-bolt yet.

 

[assault187]

That's what I'm thinking. It'd be interesting to know what the clearances are on your bearings right now. That could be the entire issue. I hope someone didn't use 7-bolt main bearings on your 6-bolt, they aren't the same from what I've heard. But I've never torn down or rebuilt a 6-bolt yet.

Im gonna hope the same thing, But I guess we'll find out soon enough. After the JMF open house (gotta show love) I'll be like a detective on this motor. Rite now im just finishing up my AMAZING 1987 suzuki samurai so its legal and I have somthing to drive while the car is down.


Every step of my progress I plan on snapping and posting pics of my findings. I will most likely be doing the AWD conversion since the car will already be apart.

 

[16g-2ndgen]

well sir i would go back to the people that assembled your block and let them know what went wrong. Them being the responsible buisness people they are, they should compensate for your damages.

 

[assault187]

well sir i would go back to the people that assembled your block and let them know what went wrong. Them being the responsible buisness people they are, they should compensate for your damages.

Well, I had brought it up to the owner after I put the motor in but got no where. I was doubted and pushed away many times....its now almost 2 years later so there is'nt a whole lot I can do now, to this day im still kinda angry but what can I do? I'll take it upon myself to re-do it, do it rite, and come out hard to keep these local tuners hating me.

 

[VETTE_50_TH]

Who did the work if i may ask? PM me if you think thats better.

James