Lurbie

iTrader: (3)

While diagnosing an engine oil pressure issue I noticed I had high crank end play on a recently built engine. It went from ~0.006" (IIRC) to 0.0115" in less than 500 miles. After reading an article on possible causes of thrust wear, I'm going through the checklist of possibilities and wonder if I have high torque converter pressures. I installed a pressure gauge at the transmission auxiliary cooler and measured pressures between 42 psi to 75 psi. Is this within a normal range for a modified (Probuilt Street/Strip kit) transmission? If it's too high, where should it be at and what can I do to reduce the pressure?

Pro Built Automatics

The pressures are correct. Call me on this.

Lurbie

iTrader: (3)

Thanks Dana, I will call you as soon as I get to the house. Here's the article I was going through:
http://www.4secondsflat.com/Thrust_bearing_failures.html

Lurbie

iTrader: (3)

Just to update and provide a more direct source of my information (as it might help others), here's the link straight from ATRA:
http://www.atraonline.com/gears/2005...005_01_064.pdf

Dana and I spoke and he confirmed above that my cooler line pressure was not excessive. In my case, I think I have high voltage drop of 0.314V. I have a new negative battery cable (that's where most of my drop was) and I will add a ground strap from the transmission to the frame rail just in case. It's about time to park the car for the winter, so hopefully next year will not involve another main bearing swap.

ASE doc

It looks like you will have to go back into the bottom end to solve the end play issue. Be sure to check the thrust surfaces of the crankshaft against the new bearing set to be sure the crank itself is not the problem. Also be sure the thrust surfaces of the crank are smooth and flat, not scored or damaged in any way.

I assume you followed a good thrust bearing set procedure -one good blow with a large mallet or dead blow(a 3 lb hammer and block of wood works well also) on the nose of the crankshaft with the rear cap bolts at about 20ft lbs- to set the thrust bearing in place before finishing main cap torque down and measuring end play. Another method is to use a feeler gauge to hold the thrust bearing tight against the block while you torque the rear cap. I learned the mallet method many years ago and have always used it.

If the thrust bearings are not properly set, this will cover up excessive crankshaft trust surface wear and make us think that thrust is okay. In this case the thrust surface of the crank will run against a fraction of the bearing surface and the bearing will wear quickly. The same will happen if the thrust surfaces of the crank aren't smooth and flat. That's why we need to first be sure that the thrust bearing fit to the crank is correct, and the surfaces in good shape. Then set the thrust bearings properly and verify end play.

MSgt Luttrell

I have seen people go through all the trouble of properly setting the thrust bearing and then use a hammer to drive on a new harmonic balancer, which of course could have negative effects on the thrust bearing.

ASE doc

Oh heck yeah. I just had that conversation with someone. Had to tell this person about a harmonic balancer installer.

Lurbie

iTrader: (3)

My machine shop (now out of business) had built the lower end. I had checked endplay when I got it back from them. I don't remember now what it was, but it was within specs at the time. When I pulled those bearings out, the front thrust face had no wear on it, the rear thrust was 0.003" thinner than the front thrust on both upper and lower rear thrust faces. So I would assume this indicated even wear and that the machine shop set the thrust bearings properly. When I installed the new bearings I set them, but only at 15 lb ft of torque based on the article I linked in a post above. I also used a 28" prybar, not a mallet, to move the crank back and forth because I feared the same concerns that happen when people drive the harmonic damper on. Having ruled out the transmission, I have four possible causes for my premature bearing wear.
1. I didn't change the oil soon enough. I should have known better, but didn't. I thought that the only reason you changed oil right after startup was if you had a flat tappet cam, I have a roller so I had waited until about 450 miles before the first change.
2. I hadn't rebuilt my transmission or replaced the converter until about 200 miles were on the new engine. That old transmission had problems.
3. My serpentine belt was too short and this caused unusual wear on the upper front main bearing. I've since installed a 20mm longer belt and the tensioner is now properly within the wear indicators.
4. Electrolysis/high voltage drop (0.314v) on the engine grounds. I have replaced my negative battery cable, bolt and installed a braided ground strap on the tailshaft of the transmission.

I have corrected all four of these items and will closely monitor my endplay when I bring the car out of storage next year. Also, while it's probably not the cause of the wear, the machine shop had installed Clevite P-series bearings. I replaced them with H-series and verified endplay of 0.0045 inch.

I am amazed at the number of people who don't even know an installer exists for that, but yes I own one and use it every time.

ASE doc

[QUOTE=Lurbie;6087540] I also used a 28" prybar, not a mallet, to move the crank back and forth because I feared the same concerns that happen when people drive the harmonic damper on.

That's why we use either a mallet or hammer with soft wood block and just a single solid blow to set thrust. Not a hammer and repeated blows, like driving on a balancer.

I would worry that the pry bar isn't enough force to set the bearings into place. But, if it works it works. It sounds like you've covered every possible cause of premature wear.