[asics0413]

OK everyone i am at the a complete loss with my rebuilt d16z6. i am on my second set of bearing in this particular engine. i believe the first set died because i didn't clean out the girdle good enough after i ground it down to accommodate the custom length rods. fair enough i tore everything down cleaned more thoroughly and replaced the oil pump and oil pan. i took the crank to my machinist and had him inspect it to be sure i caught the failing bearings early enough. he micro polished it and said everything was in spec. so i put it back together with some acl over sized race bearings with a moderate amount of assembly lube, and dropped it into the car. i unkooked the dizzy and spun the engine over to prime the oil. but when i started it i had no oil pressure. within 10 seconds of startup i shut it down and left it till the next day. again the followeing day i did the same thing and nothing. so now im looking at no more than 20 seconds of run time. at this point i take the plugs out and spin the engine for several minutes. i finally get it to prime by feeding oil into the block at the oil filter and fire it up. now im looking at 85 psi of oil pressure cold and 15 to 20 once its warm running 20w50 with zinc breakin additive. i let it run for 30 minutes and drain the oil and swap the filter. i do this twice more but i run it for an hour trying to flush anything i might have missed from the first set of failed bearings. by the third oil change i notice my oil pressure is stuck at 100 psi even after warm up. (first two were 20ish once warm) so i pull the girdle and notice lots of wear on the new bearings and lots of flakes that must be from the bearing in the oil. what i want to ask is this caused by running the engine without oil for those 20ish seconds or do i need to look for other causes. total run time is 3ish hours.

 

[BeerDrinkin]

What were the bearing clearances?

Did you have the rods checked for roundness?

Why are you running oversized bearings?

 

[rico58204]

What were the bearing clearances?

Did you have the rods checked for roundness?

Why are you running oversized bearings?

These are all great questions, especially if everything measured within specification. Why run over sized bearings?

 

[asics0413]

ok everyone i know what i did wrong it hit me on the way home and i am ashamed to even admit what i did. but hopefully this could help someone else from making the same mistake. i bought all my bearings over sized. for whatever reason it never crossed my mind that i might have over sized bearings on the rods and standard on the mains. not that i didn't know you couldn't do it i just saw a full set of over sized and slapped them in there. I'm going to tear into it today and I'm guessing the rods bearing will be fine not that i plan on reusing them. the crank originally spun a bearing btw. but thanks for the suggestions anyways.

 

[mattliston]

Did you clay the motor during assembly?

With a spun bearing problem in past, was the crank cut and polished? or did you only clean it up and use new bearings?

It is possible the crank is warped.

It is also possible (regarding high oil pressure) that the oil pumps relief is jammed shut and not releasing

 

[asics0413]

when you say clay are you talking about plastigaue?

this motor is a mis match of different parts i found on craigslist. the girdle matches the block and i think thats about it.

ill ask my machinist if he checks for warping in the crank.

i already dissembled the engine and put it in my truck to be dropped of tomorrow and i found that one of he signal wires for the oil fell off, causing the gauge to be maxed out.

 

[mattliston]

I only pick warp or bent, as its eaten another set of bearings in record time.

If its going to the machine shop, you can ask for the crank to be cut and polished so that you have all matching bearing tolerances.

That would be ideal, as then all 5 mains are getting the same oil pressure.

This assumes the block does not need a line bore. If the girdle matched the block, and nothing has ever been over-torqued, its an okay chance you dont need one. But if its reasonably priced, it wouldnt be a bad idea, if this engine is eventually going to see a lot of stress or heat

 

[saefifty]

Give your machinist the crank and buy your rod and main bearings from him to match what he did to the crank.That eliminates ending up with the wrong parts and clearances.

 

[mattliston]

Speaking of tolerances, no numbers have been posted.

If you blindly threw in a set of bearings, that is most likely the problem

 

[asics0413]

quick update on the build. i found out what my issue was. as it turns out the small black box that T's into the oil return from the head was slap full of carbon deposits and would contaminate the oil after each bearing swap. cleaned it out and took it to the tuner. now im making 300whp and 277 lbs trq!

 

[The_Acid_Beaver]

Dang, that must have been a surprise to find . . . but EVERYTHING needs to be cleaned before putting it on the engine.

 

[Hexxal]

How's your engine doing my Z6 is knocking like crazy dont know what to do, new motor or rebuild