Need some MAJOR help with this sound- tranny/thrust bearing

[SilverXJ]

This sound has been present in all engines. Those bearings are from the previous block, I haven't pulled one from this one yet as it only has 100 miles on it.

3 blocks, 2 cranks, 3 torque converters, 2 flex plates, 2 transmissions, 3 cams, and many bearings.

The current crank was checked over by 3 different people and nothing was found wrong with it.

There is no way the flex plate can be installed backwards.

This new block received a line hone because the bores weren't perfect. It wasn't off enough or a bore, just a hone.

Bennie at Hesco said it is a common problem for the torque converter snout to bottom out in the crank prior to the bolts being fully tight. While I will check into this with the old parts I don't think that is the problem as I can push the torque converter up flush to the flex plate with my hand prior to installing any bolts. But wouldn't that also but force on the rear of the bearing, not the front?

[dwg86]

This sound has been present in all engines. Those bearings are from the previous block, I haven't pulled one from this one yet as it only has 100 miles on it.

3 blocks, 2 cranks, 3 torque converters, 2 flex plates, 2 transmissions, 3 cams, and many bearings.

The current crank was checked over by 3 different people and nothing was found wrong with it.

There is no way the flex plate can be installed backwards.

This new block received a line hone because the bores weren't perfect. It wasn't off enough or a bore, just a hone.

Bennie at Hesco said it is a common problem for the torque converter snout to bottom out in the crank prior to the bolts being fully tight. While I will check into this with the old parts I don't think that is the problem as I can push the torque converter up flush to the flex plate with my hand prior to installing any bolts. But wouldn't that also but force on the rear of the bearing, not the front?

If the torque converter snout bottomed out on the crank, I would'nt think that it would push on the thrust bearing. It would bend the flex plate backwards when the converter bolts were tightened because of a gap between the flex plate and converter. The converter snout would just be tight against the crank. Also the converter isn't held at a certain depth on the transmission, it slides on the input shaft splines.

[SilverXJ]

It looks like the split line of the bearing are worn more than the rest of the thrust surface, or am I looking at it wrong?.

You are looking at it wrong. What you see at the split line is in fact a factory bevel on the bearings. Normal. Now look at the front of #1 That bevel isn't even there.

If the torque converter snout bottomed out on the crank, I would'nt think that it would push on the thrust bearing. It would bend the flex plate backwards when the converter bolts were tightened because of a gap between the flex plate and converter. The converter snout would just be tight against the crank.

That is what I would think too. It would just bend the flex plate. Now, if it bottomed out so much that it pushed the converter back onto the oil pump fully then I can see if putting pressure on the crank. But thats not my case as I need to pull the convert forward to meet the flex plate. However, why is it called a flex plate? Does it really flex to allow something to move? If the crank is bottomed it wouldn't be able to flex.

[SilverXJ]

Lee at Hesco believes the crank is to blame. http://www.hesco.us/forum/forum_posts.a ... PN=1&TPN=1

[SilverXJ]

I removed all the converter to flex plate bolts today and the converted was still flush with the flex plate. That rules that out.

I put a pressure gauge on the transmission hot line before the coolers and filter. It only read 18psi at idle, can't check it while driving. I didn't check the return line as with pressure that low in the feed line there is no reason to check the return.

I eye balled the crank rear flange and I am fairly certain the crank wasn't moving fore or aft when the noise was happening. Of course I have no way to measure that when the engine is running.

I also checked crank end play, the first time since assembly. Its .006". During assembly it was .002" but Lee made the point that the bearing could have shifted since. It only has 100 miles on it so I will keep an eye on it.

Something I have been thinking of is that the first engine with this sound showed no wear on the thrust bearing. But it was also using King bearings. Maybe the Kind bearing is a bit more durable than the Clevite?

Maybe the sound and the thrust bearing wear are a separate issue?

[SilverXJ]

Here is another crappy tidbit of information. I found the very first thrust bearing from that engine. The majority of its wear is on the REAR, where the last one was on the FRONT.

Seriously? WTF?!?!?!

[gradon]

I wish I could help you man, but I have no clue. Someone mentioned a bad crank--do you have a machinist that can check it out for you(if you haven't already done so)?

[SilverXJ]

I've already done so. My machinist has checked it out. The crank company has checked it out. And a local crank grinder has checked it out. Personally I still feel the thrust surface is too rough. I feel their definition of good maybe different than mine. Good.. as in "good enough to work in most situations" or, mine.. as in "perfect". A spare crank is off to hesco for inspection.

Im pulling to oil pan this weekend for inspection.

[Bodo]

I recommend Nick at Shaftech http://shaftech.com/index.htm

He did my crank. Top notch work. A little pricey and took a while, but was very satisfactory.

[threemilesout]

I have exactly the same problem with a 2004 I-6 4.0 liter.

It is my daily driver and after 160K the trans finally needed to be rebuilt. Had it done professionally, 125 miles later the car started making a horrible knocking and the crank moved forward and back in the engine a quarter inch. Shop told me it was the thrust bearings and that it was just time to get it rebuilt with that many miles.

I pulled the engine, had a long block rebuild done with a new crank (i paid for a new one anyway). The rebuilt engine lasted 85 miles to total destruction of the thrust bearing. Transmission shop inspected their trans with the engine rebuilder present, no determination was made. The trans shop gave me a new torque converter from a different manufacturer as insurance against their trans causing the problem. The machine shop rebuilt the engine again (long block, I saw it in pieces at their shop when I stopped by to inspect the bearings) and I put the motor back in.

The second rebuild lasted 36 miles prior to starting the same knocking noise.

Same as you, the engine only starts knocking after about 10 to 15 minutes of operation and only under a load until at full operating temperature.

Same as you, the thrust bearing was completely worn through and the crank ruined.

Mine is also an automatic.

The install was perfect, all the pressure tests on the trans were perfect, the oil pressure on the engine is perfect. All clearances were within normal limits.

The only difference is that both times the thrust bearing wore out from back to front, I do not know if it is back to front currently since I haven't pulled the engine a third time yet. No noticeable damage to the front of the bearing, though I did have more damage in the journal than you did. I do not see any bluing or hot spots on the crank or bearing indicating a lack of oil as the cause.

I would like to know if you figured out the cause or just went with a replacement engine altogether?

I suspect that I have a flow restriction of oil to the thrust bearing on my engine. It could be that something broke loose and is plugging the oil port to that bearing, a poor casting of the block that finally let something loose blocking flow, or gremlins, I don't know.

[SilverXJ]

Mine is most noticeable at idle. I believe the thrust wear on mine was due to a poor finish on the crank thrust face. However, I also believe the sound is related to my cam bearings, which is still being worked on.

As far as your problem is concerned these are the main suspects in thrust bearing wear:
-Improper crank finish
-clogged transmission cooler circuit
-ballooned torque converter
-lack of oil to the rear of the thrust face

When you rebuild your engine make sure the thrust surface is good on the crank. Also, chamfer the split line of the top bearing toward the rear of the block to push more oil to the bearing.

Since it immediately happened after a transmission rebuild the transmission would be the prime suspect. I don't know what internal would cause a transmission to do that other than some fitment issue with the torque converter. Prior to engine install make sure that the converter is fully seated on the shaft. It may take some wiggling and turning to get that to happen.Put a little bit of grease on the hole in the end of the crank. Replace the transmission cooler and lines if they are suspect. Also, keep in mind that some coolers and lines have anti-drain back valves built in. If present make sure it is oriented in the correct flow direction. Once the engine and transmission are attached, but prior to the flex plate bolts, make sure the torque converter can sit back from the flex plat at least 1/8" and that you can spin the torque converter over by hand prior to bolting the flex to the converter.

The last few pages of this pdf have info on thrust bearing failure: http://www.engineparts.com/publications/CEB-1-1208.pdf

[lafrad]

If you don't properly seat the torque converter into the transmission oil pump, this can all happen easily too. the pump will still spin and pressurize the trans, but the engine will suffer the damage.

[stege123]

Years ago, some types Torque converters had the tendency to Balloon up under pressure, ie getting longer, due to internal failure, giving the same complaints. Maybe that is going on.

[4.whoa]

That would be a heck of a coincidence being 2 tc's from DIFFERENT manufacturers.
You didn't put the little washer/ring thingie on before the flexplate did you?

[threemilesout]

Both torque converters were seated properly as best I can tell. I had to pull the torque converter forward to start the bolts through the flex plate. There was approximately 1/4 to 3/8 gap between the torque converter and flex plate prior to tightening the bolts. It also moved freely when separate from the engine.

The transmission shop flow tested all of the lines on my transmission both directions, including through the radiator. The resistance pressure was well below the minimums required by the manufacturer and they stated that other transmission related symptoms would appear at the same time as my engine problems have appeared.

The Torque Converter Rebuilders Association (TCRA) stated that some Ford torque converters in the past were prone to ballooning, but they had no documentation of a torque converter ever ballooning on any Jeep product, no matter who they were owned by at the time. All of the measurements were well within limits on both of the torque converters I have had in it.

The metal washer on the flex plate was installed between the flex plate and the bolts (ie. flex plate directly against crank, then washer, then bolts) per the witness marks on the flex plate and the exploded view in the Jeep shop manual. Trust me, I thought it could have been this one!

As far as the engine goes, I don't know what the rebuilder did or didn't do. I took a closer look at the thrust bearings from the second time it wiped out and there is visible wear to the bearing surface, making me suspect that a lack of proper oil is causing the problem. If it was the transmission, I would expect only damage to the thrust surface, but the journal surface to be clean. They are both damaged. He put a rebuilt crank in the second engine that he said he turned himself, so I can only assume that he did it correctly.

I don't know what the status of the cam bearings are since I didn't see them and the rebuilder never mentioned anything to do with the cam.

I don't know if the rebuilder brushed the oil galley leading to the thrust bearing. Witness marks on the bearing indicate that he installed it correctly. If he didn't make sure the galley was clean it is possible that something in there is restricting flow to the bearing.

I have 300 miles on the car now, mostly around town. Any drive over 30 miles warms up the engine enough and causes the knocking to begin. Otherwise, I'm going to drive it until it gets worse and the crank sensor won't read!

Also, there is approximately 1/8 inch of play forward/backward on the crank right now. There was no real perceptible movement when I installed the engine.