98 Grand Prix GT Coupe: Bad Main Bearing Rebuild Project

**jasonbernard** · 07-12-2016

Hello, new to this forum.

I recently picked up a 98 GP GT Coupe for my daughter who gets her license later this year.

I purchased it from a nice guy who didn't have time to fix it.

He filled me in on what was wrong with it, a bad main bearing, and also provided a salvaged engine (unknown miles).

This car has 60k miles on it and is in quite pristine condition, except for the faulty bearing.

I would like this rebuild to focus on reliability, not necessarily performance.

I have found a good machine shop who took the time to sit down with me and explain the rebuild process, and they seem to charge a reasonable fee within our budge, especially if my daughter and I do the disassembly and reassembly.

I understand these 3800s are somewhat known for oil leaks.

From a reliability stand point, what do you recommend for the most reliable replacement gaskets?

**buck531** · 07-12-2016

INb4 anyone else says.. just buy a junkyard motor and swap it in and be on your way.

As for gaskets? Rock auto/amazon, anything with a engine gasket kit. I think I got mine off amazon for $120ish.

**Scottydoggs** · 07-12-2016

first off, just use the used engine it came with. its not worth the cost to rebuild and the risk of it not lasting to long is always there, even if a shop rebuilds it. most cost about 2 grand, and that likely what the cars worth. who want to invest more then the whole cars worth in to the engine alone?

leave the heads on, they rarely go bad, off rockauto, look a lower conversion gasket kit, its the bottom of the engine, every last little gasket for like 30 bucks. then look up the lower intake gasket kit, find and buy the magnum kit, its 40 bucks and comes with more extra parts then any other kit.

**jasonbernard** · 07-12-2016

Buck and Scotty, I appreciate the reply, and thanks for the suggestion on the gaskets.

The reason why I was going for a rebuild is because I don't trust junkyard motors, had a bad experience doing that before on a different auto.

We have some budget to do a rebuild, and I am hoping the crank from the salvage motor we have will meet spec.
The machine shop has agreed to check out both motors for ~ 90 bucks, which I am happy to pay for peace of mind.

Another thing is my daughter wants to be an aircraft A&P mechanic someday, and the machine shop is willing to let us watch the process.

**Scottydoggs** · 07-12-2016

id would just clean the new used engine then tear it down, you and your daughter re gasket it all by yourselves paint it and swap it. theres a few weekends of mechanical bonding time

you need nothing more then a tq wrench and a 30 piece socket set to work on these cars. , maybe some larger sockets for some bolts, but its all basic tools for the engine swap.

heres the engine pull how too. full tool list too. http://www.grandprixforums.net/threa...illBoost-Style

then theres a few bolt torque threads here as well.

**WarStryker13** · 07-12-2016

With a full re-gasket, that is effectively a rebuild for these engines. The bottom end is practically bulletproof if properly maintained.

It's simply cheaper and easier, and allows your daughter to get hands on, best way to teach anything IMO.

**jasonbernard** · 07-12-2016

Thanks guys, appreciate the advice.

Do you recommend doing a leak-down test on the salvage motor first?

**Scottydoggs** · 07-12-2016

most just drop it in. other then new gaskets, some dont even do them lol.

you might want to mod the lim too. plugging the two coolant ports will keep the engine from hydro locking in the future. that plastic upper intake fails and it leaks coolant into the lower intake, thats how most na engines spin a bearing.

you could do a compression test of the new used engine. crank the engine over on a stand via the starter and jumper cables to the starter. but depending on how its been stored the valve seats could be a bit rusty and could throw the test off some.

**buck531** · 07-12-2016

You could. Take off the pan and make sure there are no chunks floating anywhere in there.

I picked this up on Saturday and by the evening it looked like this:

I didn't have to take the heads off but I'm putting a set of ported heads on anyways. Already put my Xp cam in, timing set and front cover back on.

**Scottydoggs** · 07-12-2016

looks like it exploded on you in the garage lol

primer engine block heads and lim.....

**jasonbernard** · 07-12-2016

The salvage engine came with the oil pan off, and the main bearing cap off and not marked.

Any suggestions how to get that cap back on later without relying on a 50/50 chance?

**Scottydoggs** · 07-12-2016

with that news, id get another engine. who knows what the hell the last owner was thinking or may have done to it.

most l36 engines can be found for 300 or less. with a warranty. 60 to 90 days free replacement.

or if your girl has a lead foot and would appreciate a few hp more, find and install a l67.

you just need a tuned pcm for that swap.

**JamesIvey24** · 07-12-2016

wasting your time and money on having your 3800 "rebuilt" I'm on third time of warranty from having one rebuilt, about $1400 machine shop cost into it, not including gaskets, fluids, times, etc and it's got low oil pressure, been sitting in my yard for months.

**jasonbernard** · 07-12-2016

wow, so a rebuild does not sound like the way to go - I thought it would have been the "bullet proof" way to go, albeit more expensive.

Still trying to get my mind around this.

Thanks for the advice.

**Scottydoggs** · 07-12-2016

once the crank is unbolted the blocks tend to twist, with out all that machine shop time its called a 200 mile engine, "if" that.

even with the shop time and them rebuilding it, it can still fail. why its just worth it to buy a junk yard engine and run it.

i got mine used but it was a pulled running engine by a member here. so i had a much better feeling about it then a jy engine. funny, but it was a jy engine to start with. it ran so good he could not scrap it with the car and he pulled it out and saved it.

**WarStryker13** · 07-12-2016

I've dropped a battery into some jy GPs and they fired right up, but I don't need an L36 for anything. Lol

**jasonbernard** · 07-12-2016

One more question, then I will go away...

If you had the opportunity to by a salvaged engine for $900, vs. a $900 engine rebuild from a _trusted_ machine shop, you would go with the salvaged engine?

**WarStryker13** · 07-12-2016

If the salvaged engine was a running engine when pulled, wholeheartedly yes.

**Scottydoggs** · 07-12-2016

a rebuild form a shop for 900? run, run fast.

**alenw62** · 07-12-2016

This is my experience with used engine 3800, I bought in 2009 a 99 SC 3800 from MRW auto in PA for 600.00 with 62,000 miles on it. My son has been driving the car for the last 7 years ( 80,000 miles ago) with no problems from the engine. This engine has been so good we just put it in the second body we bought for 325.00. Fun changing everything over to make it run in a SE which had a 3100 in it. Get the used engine and let her fly.