Recomendations on Engine Overhaul?

[CellerDweller]

I recently purchased my first DSM. Unfortunately it has not been initially rewarding - I'm not blaming the car for the problems, just the previous owners and more than likely lack of maintenance on their part.

Two weeks ago I had a compression test performed which was as follows (185, 185, 180, 180). The car is burning a little bit of oil, which can be seen in the exhaust. Car is a stock 1996 Eagle TSI AWD Auto with 111,000 miles - timing belt was changed at 96,000 miles. I'm currently using Amsoil 5-30 full synthetic and only mod is a K&N filter.

Recently the car lost all power and would not idle or run unless the RPM's were above 2500. I limped the car back to the mechanic and a compression test showed no compression in cylinders 1 and 2. Looks like the head gasket blew between the two cylinders, but I will need to remove the head to confirm.

My intention for this car is mostly a DD with minor mods. I am planning on going through the entire head - new exhaust valves, lifters, springs, valve guides, valve stem seals and having the machine shop check for cracks, machine flat, grind seats and valves. Any recommendations for good quality stock replacement valve springs at a good price? How about lifters and valves?

In your opinion and experience, would you also go through the bottom end of the engine at this point? I would like to resolve the oil burning and the mechanic said that the oil rings may be worn allowing oil to remain on the cylinder walls and also account for the higher cylinder pressures in the compression test.

Sorry for the long post, but I tried to include all details.

 

[92AWDHX40]

Goals stock is just fine, again budget and your needs. Start bottom, and work your way around.

 

[bsbllfit7]

If the rings were going bad you would think the compression would be less in the cylinders. Have you checked your turbo for shaft play, i would see a blown turbo seal or bad valve stem seals to be the cause of the oil burning.

 

[92AWDHX40]

Yep turbo can be bad also, check that too.

 

[bryanwheat]

Do a leakdown test before anything. I hate to see people tearing down perfectly good bottom ends for nothing.

 

[LiquidX]

I agree with Bryan, always perform a leakdown test to single out your problem areas?.

If your head gasket went, the question is WHY it went out now.

 

[92AWDHX40]

Process of elimination, check the most obvious i got smoke from mine only turbo was replaced.

 

[CellerDweller]

With no compression in cylinders 1 and 2, I'm not sure a leak down test is possible - although if the test is done on cylinder 1 and the air is leaking into cylinder 2 that would confirm the head gasket leak correct?

The original T25 failed about a week after purchasing the car - oil seal on exhaust side. I had the car brought home on a flat bed to make sure I didn't run it low on oil. I purchased a used one from the classifieds with no axial play, and a little bit of side to side shaft play but no signs of oil in the outlet of the compressor. I plan to put a T28 on after the engine and head are solid again.

I also found out after I purchased the car that one of the previous owners had the timing belt cover end up catching the timing belt and jumped a tooth bending some valves. Not sure if this is possible, but that's what I was told. That was at 96,000 miles when the timing belt and wheels were changed and the head was also gone though - I'm not sure what exactly was done to the head though except for changing the bent valves. I had the cylinders bore scoped and the piston tops look good and the cylinder walls are smooth.

 

[BogusSVO]

Ok lets back up and start with the first issue .. the smoke.
When did it smoke? at start up and pulling off from stop lights? If yes that would be valve stem seals in the head.

Did it smoke all the time? If yes, that is rings or turbo oil seals, but the turbo was replaced, so that is rings.

Now you say the head was off and at a machine shop, I wonder if the PO hd the head patched or fully worked.

If the head was patched, just the bent valves replaced, then you may have old seals and/or old seals, both of witch will allow blue smoke at start up and idle.

Making matters worse is the chemicals the shop cleand the head may have made the seals harden, allowing for blue smoke.

From your compression readings, 180-185, that looks good. So I will conclude the issue is in the head.

With the #1 and #2 cyl showing no compression, you are safe to conclude that the compression is swapping from cyl to cyl.

Now did the car over heat?
Do you know if when the head was off if it was surfaced?
Do you know what HG was used?

Now if the head was belt surfaced, that is a very poor surface, and if a MLS head gasket was used, just boosting can cause the compression fail of the HG as you are explaining.

some reading for you...

http://www.dsmtuners.com/forums/cylinder-head-short-block/420045-how-have-4g63-head-rebuilt.html

http://www.dsmtuners.com/forums/cyl...how-measure-4g63-cylinder-head-thickness.html

http://www.dsmtuners.com/forums/articles-engine-fuel/341627-how-check-head-warp.html

http://www.dsmtuners.com/forums/new...face-4g63t-cylinder-head-mls-head-gasket.html

http://www.dsmtuners.com/forums/newbie-forum/341218-how-change-valve-guides-4g63t-head.html

http://www.dsmtuners.com/forums/cyl...0613-why-not-let-your-head-belt-surfaced.html

http://www.dsmtuners.com/forums/newbie-forum/341028-4g63t-head-oil-port-mod.html

 

[CellerDweller]

Bogus - Thanks, lots of good info there. I have read some of the links that you recommended, and I'll look through the rest. I'm not sure if the head was belt surfaced or if any surfacing was done. I know it was performed at a local parts store about 5 years ago when they machined more than just rotors and drums. - I'll do some digging.

The car smoked a little at start-up and after taking off. Again, not sure to what extent the head was reworked/ rebuilt. That is why I plan to have the guides, all valves, seals, and springs replaced and head machined flat if necessary. The machine shop will lap all the valves and grind the seats. I may replace the followers as well depending on their condition. I will have the machinist do the oil port mod as this may be the second time material was removed from the head. I will also measure the thickness before any machining is done.

Failed head gasket type - not sure yet as I don't have the head off, but my bet would be a Carquest aftermarket OEM replacement. Do you have any recommendations on type of HG to use for a car that will only have minor mods in the future (2.5" or 3" exhaust turbo back and T28 with preset WG actuator boost pressure)?

The car was never over-heated for the short time that I have been driving it. The needle is always at midpoint on the gauge under operating temp.

At this point, and with all the good info given, I will plan on having the head rebuilt and leave the bottom end alone. I also plan on doing the balance shaft elimination as that probably has not been done yet.

 

[BogusSVO]

If the guides are in good shape, let them be.

The big thing is whatever shop you have do the work that they have decent equipment, as far as the seat and guide machine and the surfacer.

Have the valve springs checked, and replaced as needed. I like the BC1100 with the stock retainers.

http://www.dsmtuners.com/forums/newbie-forum/341287-how-test-valve-springs.html

http://www.dsmtuners.com/forums/newbie-forum/341209-4g63t-valve-spring-info.html

So you have a better idea of what your head should go thu...
http://www.dsmtuners.com/forums/cylinder-head-short-block/420045-how-have-4g63-head-rebuilt.html

 

[CellerDweller]

Thanks for the good info! It's great to see that there is a wealth of shared knowledge here. I will be removing the head this weekend or possibly between Christmas and New Years. I will be sure to ask the machinist what process he uses on DSM cylinder heads. He did a great job on my wife's Saturn which had a toasted exhaust valve, granted not a performance car by any means.

 

[CellerDweller]

This is an old post (it was too cold to get out and work on the car this winter) , but here's the update on what I found:

One exhaust valve from cylinder 1 and one exhaust valve from cylinder 2 had holes burned in them. Seems odd to have happened at the same time. I pulled the head and brought it to the machine shop. I read good reviews on the SS valves that Engineblder sells and bought a set, along with BC springs and a complete OEM overhaul gasket kit. The machinist will also do the oil port mod to the head. Also picked up a new OEM timing belt kit - while I have access. I measured 0.005" difference in cylinder bore diameter from bottom to top, so I yanked the engine and brought that to the machinist as well for 0.020" boring. I picked up some NPR pistons and rings, Clevite rod and main bearings - journals and pins all measured within stock specs. I also picked up a BSE kit using the Mitsu parts.

I will soon have an engine that I know the history behind - that is when I get it back from the machinist - it's been a month and a half now!

Anyway, for those that have the same symptom - don't assume the head gasket right away like I did.

 

[cliffkemp]

Sounds like everything is going well. Do not forget to have the engine balanced. If you have the money, I would recommend the L19 head studs so that you never have to worry about head lift or HG failure in the future, should you choose to mod the car even more at a later date. If you had the engine surface machined and the head machined, you 'can' use a MLS HG...Many will debate this but, as I said, this would be if you wanted to boost more in the future. This combo is not needed but, it is a good one.

Make sure your oil pump housing is in good shape and if you are doing the BSE, make sure you use the bearing with the groove in the middle!