michl0007 Posted November 4, 2007 Report Share Posted November 4, 2007 What a great site! The information here is just short of amazing. I picked up a 94 Grand Prix se for my daughter a couple of weeks ago. Was in the middle of LIM gasket replacement and decided to do a compression test before putting it back together. Here are the readings 70 140 40 170 60 124 I now have the heads off and it appears the gaskets did let go. How do know at this point if the bottom end is good enough to just replace the gaskets and reassemble? the odometer shows 95k I know this isint correct not sure how many miles are on the engine other than a miss it seemed to run ok before taking it apart. There were studs broken on the exhaust manifolds front and back and the rear exhaust manifold was cracked it broke apart when I took it off. I do not want to dump a ton of money into the, at the same time I do not believe in doing things half assed either. I plan on having the heads checked to make sure the surface is flat and in decent shape. Any suggestions would be appreciated. My question is Quote Link to comment Share on other sites More sharing options...
Chancho Posted November 4, 2007 Report Share Posted November 4, 2007 your question is... (drumroll please) Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 4, 2007 Report Share Posted November 4, 2007 But if you have the heads off, just make sure that the heads are FLAT. Once put back together. start the car and let it wamr up. change the oil. This will ensure that nothing else goes wrong... more a saftey step than anything else. Quote Link to comment Share on other sites More sharing options...
michl0007 Posted November 4, 2007 Author Report Share Posted November 4, 2007 The question or my concern is how do you know the bottom end is ok? Is it possible all the compression loss would be from the head gaskets? I think they have been replaced before most of the intake bolts were loose the exhaust manifold had two studs broken on the rear and one in the front. The head bolts were a real pain to get loose. There is not much of a ridge in the cylinders at all. in some of the cylinders you can see very faintly some of the cross hatching. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted November 4, 2007 Report Share Posted November 4, 2007 Unless the rings were bad ( which by there not being a ridge I would doubt ) then you wouldnt be loosing compression through the bottom end. For the most part, if you dont know if any coolant/water got to the bottom end, this is why you have to go through about 2 oil changed when you put the engine back together. What you missed, the oil changes will pick up and leave very little chance for anything to damage the bottom end bearings. The intake bolts being loose are not a good thing as it wasnt sealing like it should have been. The exhaust manifolds really dont have much to do with the gasket issue, but will give you an annoying exhaust leak Quote Link to comment Share on other sites More sharing options...
R Dubya Posted November 4, 2007 Report Share Posted November 4, 2007 it's common for these gaskets to fail, so don't necessarily be concerned about the bottom end yet. If it ran with the gaskets bad and there was no knock it would be a good assumption that the engine is fine. The studs breaking, both on the manifolds and the manifold cross over pipe are prone to breaking as well, usually you can use some sort of penetrator and get them loose. Those are readily available at the dealer. I also strongly recommend that you replace the bolts that hold the LIM down to the heads, they are easily stretched and recommended to be replaced by GM. Head bolt sets are available relatively cheap from Advance Auto parts, I think I paid about 20 for the set. Please do yourself a favor and take the heads to be pressure checked and then flattened. If the gaskets were bad it usually means the gaskets failed, but as a consequence it probably overheated the aluminum and warped at least one of them. Quote Link to comment Share on other sites More sharing options...
michl0007 Posted November 11, 2007 Author Report Share Posted November 11, 2007 Any recommendations on head gaskets? I was going to pick some up today and try to get this warped up. On the autozone website they have 2 different felpro gaskets listed on is SD there is a substantial difference in price. on is 14.99 and the Sd is 31.99. Are these put on dry? Quote Link to comment Share on other sites More sharing options...
michl0007 Posted November 26, 2007 Author Report Share Posted November 26, 2007 Finally got a chance to work on it this weekend after getting it put back together changed the oil added the coolant.. Turned the key and no start. What a pain in the *** It ran before the tear down although a bit rough. Rechecked the plug wires beleive they are correct based on the manual and a search here. Going to check the spark and fuel pressure, there is pressure in the rail from pressing the schrader valve. One of the wires for the CPS connector was pinched by the ac compressor did not appear to broken in two. I replaced the CPS since I broker the tab that holds it down when it was apart trying to remove it to clean the surface for the intake. I am sure that I am not the first guy to run into this. Any suggestions would be appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
RangeStang Posted November 27, 2007 Report Share Posted November 27, 2007 Double check and make sure the coil packs are plugged in nice and tight. Quote Link to comment Share on other sites More sharing options...
Chancho Posted November 27, 2007 Report Share Posted November 27, 2007 also icm plugs, there are 2 big ones on one side, and a little one with 2 wires on the other(passanger) side, also did u get no crank or just no start, Quote Link to comment Share on other sites More sharing options...
michl0007 Posted November 27, 2007 Author Report Share Posted November 27, 2007 will double check the connections. Is it possible to plug the wrong ones together. It cranks but dose not start. Thanks Quote Link to comment Share on other sites More sharing options...
Chancho Posted November 27, 2007 Report Share Posted November 27, 2007 no all 3 plugs are different Quote Link to comment Share on other sites More sharing options...
michl0007 Posted November 27, 2007 Author Report Share Posted November 27, 2007 its running. ended being the wire that was pinched by the ac compressor once I replaced a section and triple checked the plug wires started up. the coil on the passanger side had been replaced before (there is a miss so took the plug wires off the coils one at a time. ) with the plug wire off the coil arcs fromt he terminal to the coil. Is this normal it is actually loud. plan on replacing the plug wire and maybe the coil. Quote Link to comment Share on other sites More sharing options...
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