hey everyone, I have a 98 Blazer 4.3, 4 X4, 4 door base model. I have to switch out the oil pump. What is the best way to go about doing this, should I yank the motor or I have read here in the Forum in different posts about tearing apart the front diff or front axles, I don't know what all is involved that way. What do y'all think, is one way easier than the other? Help me out here please.

Thnx,
Jim

 

There is no easy way. Why is it that you want to replace the oil pump?

 

Oh Les, trust me I dont want to do it at all...you asked so here goes. Process of elimination; oil pump is last on the list.

I have a 98 4.3 that is freshly rebuilt; got it all put together and installed into the truck and one of the last things i did b4 starting her up for the first time was to prime the oil pump; took my old distributor that I had pulled the gear off and used it along with a cordless drill to spin the pump...less than 30 seconds into this I hear fluid spraying and hitting the ground. Look under the truck and there is a puddle of oil at least 18" diameter; the driveshaft; front dif; front tire and everything else in that vicinity was covered and dripping oil. It had blown out/past the remote adapter on the block...adapter had new oring and gasket and was torqued to specs. Spoke to a mechanic bud who said that in this case GM/Dealer replacement gasket and oring were far superior to aftermarket...so I got new set from dealer; checked the lines for obstruction; checked the oil cooler for obstructions; bought more oil and a new filter just in case. Put it all together and tried again with same results...another 3 quarts wasted. Talked to my bud again and researched online and ordered and replaced all 3 bypass valves; took going to 2 dealerships and 40 mile round trip to find all 3; put them in; put it all back together; bought more oil and tried again with same results....oil everywhere. So the oil pump is the last thing; must be a bad/stuck pressure regulator. So there ya go...my sob story.

 

It sounds like your on the right track if the oil pressure is going that high to blow seals.


It has been a long time since I have worked on a front diff on these blazers but if I remember correctly you should be able to just take the front driveshaft out and un-mount the front differential. you may have to wiggle it out of its mounts but this should allow the front diff to drop down a bit and give you room to remove the oil pan.
If you need a little more room you can take the motor mount bolts out and lift the engine up a few inches but beware of the distributor to firewall clearance.

 

if it's really the internal oil pump bypass malfunctioning and blowing out seals, the oil pressure would show abnormally high. Have you put it on an external gauge or watched the gauge in the vehicle while running it with the drill? Unless actual oil pressure is crazy high on a gauge, I think you will be wasting your time to change the pump. My opinion....

 

with everything i have done; if its not the pump then what is it?

 

Have someone watch the gauge, or better yet put a real gauge on it. If the pressure in the engine oil galley is not too high when it blows the seal (and yes you do need to check and make sure you do have pressure in the oil galley), then it's NOT the oil pump making too much pressure and you can forget about it being the problem. I would suspect something isn't right with the oil filter adapter. I bet the seal is blowing at fairly low oil pressure. Doesn't sound like you have looked at the pressure where this happens yet.