Fried cylinders

[92TSIEAGLE]

I rebuilt my 92 talon awd engine two years ago due to oil usage. The car has been using quite a bit of oil lately so we did we did a leak down test ( 15k on rebuilt). Cylinders 1 & 2 are blowing buy quite badly. these are the same two cyclinders that prompted the initial rebuild 2 years ago. When we rebuit the engine I replaced the ( cracked)14b with a new big 16g evoIII turbo as well as the exhaust manifold. I have my manual boost controller set for 11 lbs. of boost. with the stock injectors. The air/fuel guage always shows rich under acceleration, so i'm pretty sure it's not leaning out. I can't figure out why the same two cylinders are screwed. Does anybody have any thoughts or insight as to what could be causing the problem? any help would be great.

 

[Big Woo]

Well how bad are the cylinders, numbers please?

When you rebuilt the engine what specifically did you do? Pistons, over bore, new rings, valve job, etc.

If you don't think there is or was a problem with tuning or over boosting, then maybe there was a problem with the rebuild in the first plase, either way we will need a little more information to help.

 

[92TSIEAGLE]

Well how bad are the cylinders, numbers please?

When you rebuilt the engine what specifically did you do? Pistons, over bore, new rings, valve job, etc.

If you don't think there is or was a problem with tuning or over boosting, then maybe there was a problem with the rebuild in the first plase, either way we will need a little more information to help.

I had new pistons and rings(1st over) new bearings, water pump, timing and balance shaft belts and pulleys head rebuilt with new seals and guides etc...i think pretty much everything that you would require for a rebuild was replaced with new from the factory. as for leak down test #'s, here is what our technician wrote on the work order.

" Removed and inspected spark plugs. (white in colour and somewhat fouled) performed leak down test on all 4 cylinders cyl #1 (90 - 62) #2 ( 90 - 61) #3 (90 - 85) #4 (90 - 84) excessive pressure leak down into crankcase."

 

[Big Woo]

With #1 90-62 #2 90-61 #3 90-85 #4 90-84 that shows roughly a 30% leak in cylinders 1&2, and roughly a 5% leak in cylinders 3&4. Is there any mention of where the leaks were comming from other than the statment of "excessive crankcase leakage" One would asume that this means out of the crank case breather. If this is the case then a piston, piston ring, cylinder, or a combo of these is the most likely problem.

It could be a ring sealing issue, possibly due to excessive fuel, boost, temp, etc. In any case you will need to disassemble the motor to get at the root cause. Are you running some sort of fuel control I.E. AFC, DSM link or something of the sort? Also what size injectors are you running, what fuel pump, and has the fuel filter been replace receintly? Sorry for all the questions, just trying to help. Any N20 on the car?

In your orginal statment i noticed that you stated having a manual boost controler set to 11 psi. I was wondering why you went to the expence of buying a boost controler, if you were only going to run .5 psi above the stock boost pressure? In the free mods sections there are tweeks listed to modify the factory boost solenoid that will allow boost pressures above the stock 10.5 psi by couple of psi, that would require no purchasing of parts.

 

[92TSIEAGLE]

I'm still running the stock 450cc injectors with a walbro 255lph pump. The fuel filter was replaced at the time of the rebuild. The rings are blowing by for sure. I set the boost at 11 psi at break in and never messed with it afterwards. My intention is to put 550cc injectors with a GM maf and an AFC. I'm crossing my fingers I can just do a rehone after I find the root cause. I have a list of all the mods done in my profile. I will be adding the mentioned items at the time I rebuild.

 

[92TSIEAGLE]

I'll aslo be adding an adjustable fuel pressure regulator.

 

[dnhieu]

i dont really know what to tell you BUT you know your getting blowby from the piston rings. you obviously know that you will be tearing her down and rebuilding again. i would let whoever does your machine work make the decision on if it needs to be bored and honed or just honed.

did you have that walbro 255 in during engine break in??? if you were running pig rich during break in you could have been washing your rings away for thoes last 15k miles. during break in i would much rather be in the lean side over the rich side...

 

[92TSIEAGLE]

The Walbro has been on the car for over 3 years. I'm thinking if it was really running rich it would have washed all the rings. I now it's running more on the rich side with the amount of boost that the car is set att. but the car has always ran really well. it still runs well given the amount of blow by it has.

 

[dnhieu]

i bet its running really rich now. i know in my case that i was getting alot of blowby (not caused by the pcv valve) and i was running REALLY rich. i think mine was caused because my timing was off. i was only getting like 11hg vacumme at idle. i have since fixed that tho and i am now getting 20 like im supposed to!