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Mpierick 01-26-2012 07:58 AM

GT block Interchangeable with the S4 block
Rebuilding my 1988 S4 engine . Can I use a 1989 GT block? Also where on the block is the block type imprinted? Thanks a lot.

Danglerb 01-26-2012 08:31 AM

Motor ID is stamped into a flat spot at the top front of the block, look straight down from the upper hose to the radiator and you should see it, something like M28/44 and serial number.

89 GT is a rare car, the block could have some value to a numbers correct owner. You might want to consider selling it. I think it should work though.

Mpierick 01-26-2012 10:05 AM

Thanks for the information.

Mrmerlin 01-26-2012 10:36 AM

can you please add more info about what your doing?
Why use a GT block what happened to the S4 block?
The girdle of each block is machined to each block.
so these parts must be kept together.
Piston assemblies must also be of the correct tolerance group,
stamped above each bore 1,2,3

Mpierick 01-26-2012 01:41 PM

My engine has locked up. I suspect the thrust bearing only because I inspected the flex plate and it was bent forward. I have not torn into it yet. What I have read is that the block and crankshaft becomes scored and unrepairable. I am also looking for a complete engine.

Mrmerlin 01-26-2012 02:46 PM

if you had thrust bearing failure then the whole engine is now contaminated with metal as well as the oil cooler. If so then the valve tappets should be replaced unless you can take them apart , the cam journals may also be scored so new heads may be needed .
A complete engine would probably be the best course of action to repair the car also flush out or replace the oil cooler.

The oil can be checked by getting a sample of the oil dripping it onto a black piece of cardboard,
then looking at the oil in the sun you will see lots of metallic particles , if so then you can figure thrust bearing failure

MarkRobinson 01-26-2012 03:16 PM

drain plug should have flakes of steel all over it. Oil filter too.

tmpusfugit 01-26-2012 04:00 PM


Originally Posted by MarkRobinson (Post 6519803)
drain plug should have flakes of steel all over it. Oil filter too.

Actually, are not flakes of aluminum? In my very limited experience with 2 failed engines the flakes were all aluminum....didn't find any steel flakes at all....:D

Danglerb 01-26-2012 09:22 PM

First step, find out what is actually wrong with the engine.

Mpierick 01-27-2012 03:58 AM

I want to thank everybody for their help. There is a lot of insightful information. I will start with the oil. I do not know the history of this car, but looks like a fun project especially with all the help. Thanks and I will keep on posting with my progress.

Sapientoni 01-30-2012 07:36 AM

I just completed the knuckle busting part of your project. I'm now into the head scratching, hair pulling part of "why the !@#$$ won't start. Slowly eliminating possible reasons.

stepson 01-30-2012 09:50 AM

Give us additional symptoms and what you have done so far. There are some really smart folk on this forum that might be able to give you guidance.

Mrmerlin 01-30-2012 04:38 PM

can the engine be turned by hand?
do the timing marks line up?
Are there metallic specs in the oil?

Mpierick 02-01-2012 08:39 AM

I am in the process of removing the engine from the car. I cannot turn the motor over at all. I drained the oil and could not see any metal. The oil was pretty thick. I purchased the car knowing the engine did not turn but the former owner did not know what happened except it stopped running. I will have the motor out by this weekend and plan on looking in the oil pan first or is there any suggestions on the sequence I should take on investigating the problem. All this help is appreciated.

MarkRobinson 02-01-2012 08:43 AM

Could be a dropped valve: keeping it to rotating: try rotating it a wee-bit backwards.

Also is the engine disconnected from the drivetrain?


Mpierick 02-01-2012 10:14 AM

Yes I have separated it. There are only 8 bolts left to bring it out. The engine mount bolts. I do not get home until after dark so I am going to wait until Sat. I will try that. Over the last 2 weeks I was thinking maybe the pistons might be frozen so I poured some transmisson fluid to break it up. No luck yet.

Mpierick 02-01-2012 10:56 AM

By the way I am still looking for a short block or an entire engine. The GT block was not a GT block. It was an S4. By the time I was ready to buy someone else bought it. Oh well.

Mpierick 02-02-2012 04:42 AM

Last night I tried to rotate counterclockwise. It is frozen in both directions. This weekend I will pull the engine and look inside. I am very curious what is locking it up. I will post with my findings.

Danglerb 02-02-2012 09:47 AM

Locked up might not be so bad, whats the history?

The DMV often shows 89 to 91 as S4 GT which can confuse people, but a GT motor is worth twice or more what a S4 is.

Mpierick 02-03-2012 05:25 AM

The car is a 1988 S4. Engine is a 5.0L 32v M28/42. I purchased the car from someone who does not have any records and could not tell me what happened. I believe he bought it and then just turned around and resold it.

Should I take the heads off first or work below and open up the oil pan. I have the engine 99% out. I just have the eight motor mount bolts left to remove. Thanks.

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