Thread: 1999 GT Coupe

I am picking up another Grand Prix! This is a 1999 Green GT Coupe with 200010 miles on it - with issues... The guy drove it to work, then after work it would not turn over, something's locked up, the starter tries but nothing happens. I failed to pull the dip stick when I was there...

I looked at it during lunch today, it is covered in snow. Kinda tough to tell what's wrong while I was there in my work clothes etc. $200 and its mine. One of my current 3 Grand Prix's needs tires so this will work. I'll go get it with my truck this weekend, it's only about 10 miles from my house. The Diesel won't even break a sweat pulling it home.

I have not met the owner, a very good friend told me about it, so I have no idea of the history of it. I do see some body damage on both sides, not too happy about that, but again the tires look to be very good and I'm sure I'll find other parts that I need.

Could it be as smiple as the starter being locked up? Pleae let me know your thoughts.

Thank you!

Well I'm not sure what exactly your problem may be..but my GP at one point had a chunk of the starter break off in the fly wheel causing it to lock up. New starter and pick the pieces out and viola.

Well I am taking the starter from this car to be tested today, hopefully this is the problem. Yesterday I found I could turn over the engine by hand, with a wrench on the crankshaft.

I can crank this motor backwards almost 360 degrees until it locks up then the starter will turn it over forward until this spot. I'm something locks it up - could it be hydro locked on 1 cylinder? I was pressed for time last night so I did not get any further.

The oil was over full on this car, and there is a film of coolant in the oil, so I am sure I need to replace the upper and lower intake gaskets - that is if it will run. Or I just need another engine. Or I just take off what I want and part it out, junk it etc. Tires are in great shape so I got what I needed, yet the idea of driving a 4th Grand Prix excites me...

Also is there a easy way to remove the spark plug wires? Is there a plug removal tool? As most everyone knows they are stuck on the plug really well. I just don't want to break a wire, smash my fingers, etc...

FordMan77 - Thank you for the info, hopefully tonight I can get time to do this! And I'll folow your instructions Exactly as you stated!

fyi - My '97 F-350 with a 7.3 and auto trans did not help get this home, the trans went out last Thursday...this will be a huge expense. I pulled it home with a 03 Duramax.

VGPGT, it most definitely sounds like your UIM failed and and that it hydro locked. If i remember carefully, cylinder 1 is where mine locked too.
DO NOT drive it please. My dad put new LIM gaskets on mine when we first bought (apparently they drove it with coolant in it for quite some time) and new plugs and he thought it was fixed. However, it wasn't. We got another UIM and it ran for a month maybe then spun a bearing.

So yea, pull off the UIM, if you see coolant there like this



then you know your problem.

Also you will know if you hydro locked most likely if you see a plug looking similar to this (or smell like coolant) as my oil was very over-filled with coolant.



Best of luck. And most definitely do what Fordman said. Do the job, drain the oil, fill with oil, crank and run for minutes only, then do another change.

Brandonl2000 - I just took off the plug from piston #1 and it was wet like yours in the picture! I turned the engine over with the socket and rachet and anti-freeze did come out. Thank you!

Going back out now to start taking this apart. Looks like I found some good instructions on here.

Yup. Just make sure you don't run it with coolant in there. Fix the problem first.
You can replace the plugs if you want or do what we did (because we had brand new plugs in it) and pour some gas on them, light it up and let it burn off. Re-gap and re-use.

Well I'm going to try to save this engine. I'll probably order the UIM and LIM gaskets from Rock Auto - any certain brand I should get? Or should I just get them from O'Reilly's?

I did not get too far last night, next real chance to work on this will be Friday night, but its also rather cold here in Western Wisconsin this week...

Well it appears thee is some internal damage to this motor. I could turn over the engine by hand - with a socket and ratchet. But after putting thais all back together the starter was working very hard to turn it over and it was making some aweful noises.

So if it is indeed bad can I take off my brand new gaskets and reuse them?

How many cylinders did you empty coolant out of? if only one..then you need to pull all the plugs and crank.

Well I removed all spark plug and there was coolant in the rear passenger side. After turning the engine over without spark plugs, I then installed new plugs.

Now this engine does not start... Seems to back fire every once in a while but nothing else.

Any ideas?

Pull the plugs and dry them off. There's a ton of coolant in the cylinders from the UIM bursting. You fixed that right?

Now you need to clear the cylinders of the water to get the plugs to fire. If you can get 3 firing and give it some throttle...it should spin fast enough to clear the others...

Yeah..been there, done that.

Bill - Thanks I was wondering about that.

I did replace both the upper and lower intake gaskets. I'll remove the spark plugs and do it again plus I'll clean up the plugs. Maybe I can do this Friday evening for I'm busy with working 2 jobs today and tomorrow.

This is the longest slowest repair ever... I just hope this car runs after all this.