wafoogalla

I blew the HG in my 88 4runner 3vze after less than a year on the new top end. Instead of rebuilding my potentially cracked block (oil in coolant before and after rebuild) i decided to buy a motor.

I bought a core from a fella on CL for probably too much. I said it had a slight knock. As soon as he heard it he turned it off and only started in to show a mechanic. By just listening, not even touching the truck with a tool, the mechanic said it had a rod knock and needed a new rod in #6. In my exoerience with this kind of half*** diagnosis is that mechanics dont like to give out free advice and dont want to put in the extra effort.

I pulled the bearings out and found no damage except for #3 which had a tiny, tiny gouge in it i could catch my nail on. The crank looks fine but was recut once before. There is no play in the rod-wristpin or rod-crank bearings. I am waiting for the rod bearings to arive, then platiguaging the journals.

My question is what else should i check while the motor is out of the truck? It is upsidedown on a engine stand now. I have not heard the motor run but im trying to inspect what i can before i put it in.

Oil pump?

Main Bearings? If so how to check?

Injectors? If so no big deal because i have to put my old ones in anyway (88 = 2-3ohms)

I know that a sucked valve is a possibility but im trying to rule out everything else before i pull the heads off.

Why would a mechanic tell someone to replace a rod when they havent even checked the bearings? In what scenario would you have to change a rod without having to overhaul an engine?

BamaYota1

Because most of the time there is a reason the bearing went out. Normally just replacing bearings is only a bandaid solution, especially if there is a groove in the crank journal deep enough to catch your nail. That journal could be out of round, or the rod itself depending on how long it was really driven like that. Why did you pull the motor to change rod bearings?

You can pull the caps to check the main bearings and plastigage. There is a specific bolt sequence to follow to loosen the caps in the FSM.

Also, you should go ahead and change the front and rear seal. Get the innards of the motor as absolutely clean as possible or debris could suck right into your new rod bearings.

If it is going to take a while before you are ready to put everything back, you can sen your injectors to witch hunter to be reconditioned. I think it's 21 an injector and they will send them back in a few days.

wafoogalla

I didnt pull the motor. I bought it from a guy on CL. Im just looking for any other possibility that it could be. The crank has no visual or tangible sings of wear, the bearing was the damaged part, but i will check with plastigauge. My toyota mech from down the road has been working on this engine for years and said this kind of wear wont make a noise over the hum of the motor. Hopefully my part comes in today.

Co_94_PU

iTrader: (-1)

Inspection is supposed to happen before you order parts, which you've already ordered so I know you're not follow the steps in the right order Not to be mean or anything but you're not equiped to inspect these parts. It requires precision and specialized equipment to do it "right".

Follow the step by step inspection directions in the manual. If you want it "right" this is the only way.

It goes something like this.. Guage the bearing gaps, measure the bearings, inspect the crank and rods, if the crank needed ground they give you the new measurement which you math with the plastiguage and bearing measurment, now you know what size bearings to order.

These are very tight tolerence parts, thousandths of an inch. I know it doesn't sound like much but once you're up to running speed there are large forces involved, and they'll make a hellofa racket.

Crankshaft mains inspection is no different than the rods, guage, runout, and micrometer in a jig.

For a "budget" repair it's still a good idea to pull and inspect everything, eg oil pump & injectors which you mentioned. basicly anything you can pull off and inspect cost you nothing but time. replace repair or refurbish anything that is out of spec tolerence. You don't want a part that costs peenys on the dollar to ruin your rebuild, eg oil pump.

As for why the guy said a rod or lower end noise, thats where he thought it sounded like it was coming from. He did it for free you can't expect him to put any real effort into it guy makes 45$ an hour

You could of/should of have listened to it with a stethoscope(long screw driver, length of 1x2) and isolated where the noise was coming from. 'Cause now you have to do a full teardown and inspection, or randomly throw parts at it.

I know some the above may sound a little harsh and I'll appologise, but you need to go by the book it's the only way to know for sure. If you have any questions about the steps ect ask and people will be happy to help.

Don't forget to inspect for un even marring/wear on the bearings these will indicate bent rods, eg more scar/wear onthe front of the bearing vs the rear. The wear should be uniform across all the bearings also, eg #1 looks like #2, these indicate blocked oil passages. You'll also atleast want to inspect the cams for uneven wear, that would indicate cam bearing issues.

Good luck, and stick with it nothing that can't be solved with some effort!

Co_94_PU

iTrader: (-1)

P.S. You're not generally going to be able to feel a sub 100th of an inch of play.

wafoogalla

I understand the necessity for a full inspection and I take cunstructiove critism well. Best case scenario would be i just replace the bearings. Parts store called so i will pick them up after work and torque them down on some plastiguage. I know it wasnt very bright of me to buy a motor with this kind of problem. The bearings do have a little wear, the coating is gone on some parts but when i put a micrometer on them the surface is uniform.

What is the possibility of being able to take the crank from my old motor to replace the new one if it is out of spec? The old motor ran like a dream other than the oil in the coolant. Rumor has it, 88 had a few incidents with cracked blocks.

I dont need to worry about the injectors because i have the old ones and they were quiet. Basically i have a whole nother motor eccept for the block. I am trying my best to avoid spending more money but i will spend it on whatever is neccesary. Its not my primary vehicle but its my baby.

p.s. what i found was #6 bearing was damn near new. Ive always had a thing against a mechanics diagnosis. I guess i dont like to pay $60 dollars for some information i can find out for free. All information is appreciated. Thank you

Co_94_PU

iTrader: (-1)

Cranks and blocks are matched up by some grey beard guy at the factory, uh we hope , that has measurements for each and then he picks/matches the bearing. IIRC there is a stamp down there, I don't recall where I saw that or if it's for the block the crank or the bearing, most likely the bearing. Might be in the FSM..

Someone else will have to chime in here cause I'm not certain.

wafoogalla

Well all of my specs were right. The widest one was .003 and the FSM says .0031 is the max. I put it all back together and sealed up the pan. Today i will pull a valve cover and check all of the clearences. Im kind of hoping this guy just had a loose bolt on his fly wheel and never noticed it. Also two of the spark plugs were cross threaded in a quarter of the way and the rest of the treads were dirty so maybe they screwed up and never noticed