i have a 98 blazer LT with a seized engine. only 122k. this does not have the zn4 build date code. i have found a 99 with w vin code like mine but it says for a zn4 build date. what might be the difference, if any, and would it work in my truck. hard to find a decent engine this old. thank you very much....david g.

 

Can you post pics of the engine? There are a few differences between the 2nd gen engines...

Maybe someone with more knowledge will answer soon...

 

99 in a 98 will be just fine. Difference will only be in rocker arms and valvetrain IIRC (99 should have the roller rockers). If there is any difference between the parts, use your 1998 intake/exhaust manifolds and brackets and oil pan and wiring harness. Always use your original PCM. Replace the intake gaskets before installing new engine. Have a crankshaft sensor relearn done after all is together and running good (probably will display SES light with misfire codes until you do). Good luck

 

thank you mr. les myer!!!!! i really appreciate your info and time. im going nuts with this project and just realized will have to pull the engine with the torque converter attatched. the motor is welded together......so if i put in a new crank sensor and start it up, the computer will notice and relearn? do i get a 98 or 99 sensor?? THANK YOU AGAIN!!!!!!! DAVID G.

 

Crank Sensor Relearn needs to be triggered by a capable scanner. No need for a new sensor. They dont wear out.

Getting engine out with converter attached will be problematic. Tends to damage converter and front pump/input shaft in trans if not very careful + clearance issues. Is this a 4WD or 2WD?

I should clarify that you should not switch pushrods or rocker arms between the engines

 

its a 4 wd. im going to release the motor mounts and jack up the front of the engine maybe enough to drop the oilpan and remove rod bolts and loosen main caps and see if that will let me turn the crank to remove the torque converter??? if that wont work-------guess ill have to blast...i have a cheap auto zone scanner...probably wont work....thank you again mr. les myer. david g.

 

I would imagine it would be much better and less chance of damaging things to just go ahead and 1) pull the transfer case and then 2) the transmission with the converter left in place - you have a straight shot to the rear with the trans. No such straight shot forward when taking out the engine. You might be able to leave the transfer case sitting on top of the rear crossmember out of the way - or maybe not, I never really tried it - just noted it. I've never heard of anyone getting an oil pan off of a 4WD Blazer with the engine in. If you get help and have a floor jack, taking the trans out first is much less likely to damage anything, plus you will be able to get to the bellhousing bolts, ground straps on the back of the heads, and the fuel line clamp on the back of the driver's head once the rear of the engine is hanging (these are ALWAYS a BIG problem on 4WD Blazers) when removing the engine with the trans in place. Then the engine will still need to come up in front above the diff because of the torque converter still being attached. Normally they would come out and go back in straight up and down even with the water pump on, but not for you. Don't forget to take the distributor out completely so it doesn't get crushed when the engine is hanging. Be careful with letting engine hang completely by itself - Blazer mounts have a habit of breaking. Don't break the A/C evaporator case with the right exhaust manifold (it comes up underneath it when raising the engine) you can usually twist the engine to clear (but maybe not with TC attached - don't know). Better I think to just remove it and keep engine straight. Don't try to take the EGR tube out of the driver's exhaust manifold. Lot of WD40, soaking, and patience with the nuts on the exhaust manifold studs. Soaking multiple time and turning back and forth, not brute strength will most likely get them off. Watch for broken studs on the new (used) engine exhaust manifolds too - you may be able to use them. Taking the steering shaft loose from the gear will help with clearance for the driver's motor mount. Taking the passenger exhaust manifold off gives you nice access to the starter and the right engine mount. Don't forget the oil pan to trans cooler line clamp or you will bend up your cooler lines. You really have to "peel" the engines out of these Blazers in layers. Take lots of photos so you know where things go back.

Always be safe and use good jack stands and floor jack and cherry picker. Have someone around. You only have one life. These 4WD Blazers weigh over two tons!

Vident I-link400 at $150 is the least expensive scanner I know of that will do crank sensor relearns. Otherwise it will need to go to the dealer or a shop that has the equipment for the relearn.

Good luck and keep us posted.

 

hey man, i just came in from working on the blazer and let me tell what i did. i took off both heads yesterday and sprayed the pistons really good with wd40po. i have used that product many times and its the best i have seen. i went out at about 10pm to let the dog out and went over and sprayed them again. this morning i took my framing hammer and hit the pistons with good sharp licks and did that several times and then put a pipe wrench on the crank and used a good cheater bar and after a few attempts broke it free. i have turned it several times and should now be able to look thru the starer hole and remove the nuts off the converter and pull the engine in the morning without worrying about the converter and pump!!!! the cylinders are pretty dark but not scored or scratched. the plugs looked ok even. i think most of the damage is going to be in the crank and maybe the rod bearings.. this engine got damaged because one of the oil lines ruptured and oil blew out every where. i did not notice anything wrong as i was driving. i was pulling a trailer with about 1000lbs on it and drove about 30 miles before it locked up. there was no stink or smoke coming from the engine. im sure my oil pressure guage dropped to zero, but i didnt see it.......oh well, i sure do hate what happened. that engine only had 126k on it. i bought this truck from a family friend whose mother bought it new and then when she died they offered it to me. when i bought it 4 years ago, it had 86k on it...dont find em like that too often. i really do appreciate all the info and advice and time you have spent helping me with this project. it is awesome to have someone reach out with their time and experience and offer so much...i cant thank you enough....ill let you know when i get another engine and get it running. THANK YOU LES MYER!!!

 

Glad things are looking up. Keep us posted!

 

i am having a hard time finding a 98 or 99 4.3 for my blazer. plenty of 4.3s out there, but are used up......i have a 98 blazer built in 02/98 and would like to know what is the latest model engine i can use in this truck??? thank you again for your time and info.....david g.