KetMalice

1986 GMC Jimmy 2.8L 4x4 with 215k miles, automatic.

My first car was an old 86 Jimmy, so I purchased one that looks good but has some mechanical problems!

Basically the engine has 215k miles on it and on idle the oil pressure goes to 0. I had a tune up done but it didn't seem to help anything. The engine is sluggish (possibly catalytic and smog pump problems). But I know the engine is on it's last leg.

I would like to rebuild/replace the engine. I will not be doing it myself, I will be having a shop do it. I already spent a small fortune on everything but the Tranny/Engine. So I would like to get it running properly, but the cheapest route I guess.

If I drive on this engine until it freezes will that damage something that would cost me more to rebuild it? Would I be better off dumping a 3.4 or 4.3L in it? From some basic research I know a 3.4L is an easy fit for my vehicle. What about a 4.3L? Where would I even buy an engine if I went that route?

I am in the OKC, OK area if anyone happens to know a place around here. And thanks for any help.

MUoffroader

First, does the oil pressure gauge work? If the engine doesn't have any oil pressure, you would definitely be able to tell that it is running like crap. BUT, if you want to just fix it the right way, that is doable as well. Driving on the engine until it completely locks up would make it not-rebuildable. As long as the engine has oil and you are planning on rebuilding it anyways, you are probably fine.
As to other engines, the 3.4 liter is really your only choice. The 2.8 and 3.4 use the same block, they just have a different bore and stroke. A 4.3 would not bolt in, and you would have to change the engine mounts and transmission, as well as a couple little things. If you were to go with the 3.4, you could find a donor engine and basically use all of the accessories off of your current engine, with a few minor little things. A good shop would be able to do the swap.

neo71665

The 3.4 and 2.8 are not the same block. Anybody that tells you otherwise can be discredited on the spot. The 3.1 and 2.8 are the same block, the 3.4 shares the same gen 1 60 degree v6 block design but was cast to handle the larger bore.

The 60 degree v6s share nothing in common with the 90 degree v6s. Bellhousing bolt pattern is different. Upper and lower rad hoses on different sides. Exhaust y pipe is diferent.

3.4 is a direct swap for a 2.8 and I've been running one for awhile in my 87 blazer. Sadly its not enough for the tires and axles I'm putting under it so its getting swapped for a 5.7.

All the extra trouble it takes to put a 4.3 in is exactly the same as putting a v8 in. With a v8 at least you have the power of vs only getting crappy v6 power with v8 mileage and the v6 tring to shake itself apart due to a crappy design.