Swap 2001 engine into 1998

5.0MX5

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1998 Park Avenue, 2001 Park avenue
Yes there is a question, it's at the bottom.

I finally found my PA (base) last year. a 2001 with 70,295 miles. Over the past several months I did ALL the preventative maintenance required to have a trouble free car (well, as much as possible anyway) this was right down to changing the brake fluid. Last thing on the list was new rear shocks for the self leveling system. Got it done two weeks ago and on a 10 mile test drive it was great. Then while almost back home, two deer ran in front of the car and the resulting off road trip wiped out the engine cradle, pushed the engine into the fire wall and the car wound up on it's side.

Now, the engine and transmission are still good..

So, I bought another (same color) base PA, a 1998 with 135,000 miles and a bad engine.

The 98 has coolant in the intake an easy fix, however the '01 had a new improved intake, both gaskets changed, water pump, and all the other the other known gotcha items dealt with.

I've already pulled the '01 engine and I see the passenger side motor mount is different along with the fuel injector connectors along with a few other easily changed bits.

I'm debating taking the perhaps easier route of replacing the '98's upper/lower gaskets along with the intake and hope it's a good engine. However the '01 is lower mileage and very good.

QUESTION: Will the motor mount (passenger side) being different or the injector connectors being non-compatible be a huge issue? I can't tell 100% if the '01 block is drilled and tapped appropriately to accept the '98 mount.

Thanks for any help or suggestions!

Ron
 

Alan 55

Buick Newbie
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Florida
Buick Ownership
2001 Buick Park Avenue, previously owned 1997 Park Avenue
I can understand your situation. Wish that I had experience in an engine swap of the type that you describe. I can only say what I would do if faced with this type of issue. My strategy would be to take a trip to one or more salvage yards with camera. We have a large you-pull-it yard with thousands of vehicles placed by make and model. All GM products together, Buick’s together and even Park Avenues together. The cars o
 

Alan 55

Buick Newbie
113
34
28
Florida
Buick Ownership
2001 Buick Park Avenue, previously owned 1997 Park Avenue
Message continued. The cars in the salvage yard are in various states of disassembly. Some may have fenders removed for a close look at the engine mounts.
It may be that you do not have such a salvage yard to access but wanted to mention the possibility.
 

MelsRegal

Full Member
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Regal GS 2017
you have both engines in front of you and will have to determine if the mount is an issue. Concerning the connectors you have to install the complete 01 engine wire harness and ecm into the 98.
 

5.0MX5

New member
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Buick Ownership
1998 Park Avenue, 2001 Park avenue
Thanks all. I decided to take a chance and tore into the '98 today. As suspected the lower intake was full of coolant. When I started removing the upper intake the bolts were barely finger tight. It appeared all was original so that's a bit of a mystery as to why. That said I went ahead and removed the lower intake gasket and the valve covers and am about to make a RockAuto order. Sure wish there was a way to make the stock intake plenum work since I now have two shockers that appear to be in near new condition. But a new one will be ordered tonight. Hopefully parts will arrive and by the weekend I'll see if this unit will run and drive.
 

Alan 55

Buick Newbie
113
34
28
Florida
Buick Ownership
2001 Buick Park Avenue, previously owned 1997 Park Avenue
Please don’t forget to order some metal coolant elbows to replace the plastic ones. The plastic will crumble and fall apart at some point.
 
109
3
18
Buick Ownership
1998 Buick Park Avenue
Speaking of the coolant elbows, I have heard about this and see them on amazon, but WHERE are they? Like, I guess I dont realize where they are. Also thanks gm for cheap crappy plastic ones when metal is marginally more expensive and lasts longer.
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109
3
18
Buick Ownership
1998 Buick Park Avenue
Would this coolant elbow be the same on a supercharged engine? When I do my alternator and supercharger coupling it might not be a bad idea to do the elbows if they havn't been done in mine yet(plus, Im changing the coolant)
 
109
3
18
Buick Ownership
1998 Buick Park Avenue
iS this by chance the same issue on series iii?
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5.0MX5

New member
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Buick Ownership
1998 Park Avenue, 2001 Park avenue
Update: Decided to see if the '98's engine was repairable. Found the lower intake gasket was junk/leaking to the point there was a hole eroded in the aluminum intake to atmosphere. The lifter valley was full of oily antifreeze and the upper intake and throttle body was full of crud. The upper intake actually looked pretty good with no signs of any problems but I changed it to the newer generation intake along with both gaskets and a different lower manifold. After a lot of cleaning and flushing with water (removed the thermostat for the flush) all the old coolant was purged, I added new antifreeze, changed oil and cranked it up.

It runs sorta OK. Still chasing a rough cold idle with the occasional small cough (backfire?) at initial crank-up.

Big issue now is the transmission. It doesn't down shift out of overdrive when it should, leading to a lugging situation.

More troubling is the transmission is noisy. Guess I was spoiled with the Super Quite 80,000 mile'ish '01.

Any thoughts on the transmission are welcome.

I should receive 12 qts of Mobile Dexron VI that'll go in along with a new filter in the next couple days. Will see what that does.
 
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