Low Compression

dead90TGP · November 08, 2008, 12:13:48 PM

Hi! I have a 1990 TGP with only 76k that was, at one time, my daily driver. It started with a random stalling problem that turned into a non-starting problem that no one seemed to be able to cure so I took it off the road for awhile until I had the budget to fix it right. Well, awhile turned into almost 2 years and now the compression is very low. My mechanic replaced the timing chain as it had some slack in it but we still have very low compression. Any suggestions as to what to look at next?

R Dubya · November 08, 2008, 12:58:29 PM

do you have numbers for the compression levels per cylinder? Did you change the oil before initial start up after the 2 yr hiatus? Try adding a solution called Rislone in place of 1 qt of oil on the next change, it's good for cleaning buildup on rings and lifters.

dead90TGP · November 09, 2008, 06:41:29 PM

The front 3 cylinders were at 50. The back 3 were not checked. An oil change was done as well as new plugs and wires.

TGed · November 09, 2008, 07:19:28 PM

Something is not jiving. Rockers all nice and tight?

R Dubya · November 10, 2008, 04:31:20 AM

yeah thats probably something Rislone won't fix. If the fronts are that low there is obviously something going on. Did it overheat ever? Burn oil?

Dark Ride · November 10, 2008, 09:45:25 AM

Rebuild? Could be anything, but for all 3 to be that low. Warped head/bad headgasket?

dead90TGP · November 11, 2008, 04:48:04 PM

The car never overheated, nor did it burn oil. The car ran quite nicely until it started with the random intermittent stalling. Certainly no signs of head damage. I love the car but I'm not sure I want to sink a ton of money into a rebuild.

TGP Nick · November 11, 2008, 06:07:01 PM

Coolant in the oil? Oil in the coolant?

dead90TGP · November 11, 2008, 06:49:43 PM

The oil was clean when we changed it last week. I'll ask the mechanic about the coolant in the morning but I would think he would have noticed that.

mfewtrail · November 11, 2008, 10:19:23 PM

I would verify the compression with another gauge besides the one you used already. ;)

Dark Ride · November 12, 2008, 09:50:38 AM

Quote from: mfewtrail on November 11, 2008, 10:19:23 PM
I would verify the compression with another gauge besides the one you used already. ;)

x2, good idea

dead90TGP · November 12, 2008, 10:54:41 AM

Compression has been verified at 50 on the front 3 cylinders, 100 on the back 3. In response to an earlier post, no oil in the coolant.

dead90TGP · November 12, 2008, 10:57:50 AM

Can the motor be replaced with a standard 3.1 and just transfer the turbo-specific parts, or are there internal differences?

R Dubya · November 12, 2008, 02:44:09 PM

realistically it can be done but there are several major and probably dozens of minor details to deal with. The oil pan would need to be swapped, the oil pump upgraded, intake and exhaust manifolds changed, I'm not 100% on the heads, mainly top end stuff. It's not a direct drop in, but it can be done.

killinprixs · November 12, 2008, 03:22:48 PM

1990 NA 3.1s have different heads, the 91-93 comes with the same head as the TGP.