ACL rod bearings after 150k kms.

[Gareth]

I usually avoid doing anything other than lurking on most forums, but Sheldon suggested that I post up a pic of what the ACL bearings I pulled out of my truck looked like after 150k since a lot of people feel that once you've changed the oem ones out you're safe.

According to the previous owners it was synthetic oil every 5k

 

[Gareth]

Probably should have mentioned that it was out of a 1990 1hdt.

 

[gerg]

What oil was used?

 

[ForealBoreal]

Got pictures of the other shells?

 

[Dougal]

100k routine maintenance.

 

[powermad]

Without having the shells in hand, the spot in the center looks like debris on the backside of the shell.
The other wear looks to be fatigue wear.

Red antifreeze mixed with oil will do similar damage.
Just about looks like shells from an engine I am fixing that had coolant mixed with the oil for an extended period.

 

[Dougal]

Without having the shells in hand, the spot in the center looks like debris on the backside of the shell.
The other wear looks to be fatigue wear.

Red antifreeze mixed with oil will do similar damage.
Just about looks like shells from an engine I am fixing that had coolant mixed with the oil for an extended period.

There is a japanese research paper on cavitation in the bearing shells of a 6 cylinder diesel engine. One of the authors of the paper is an engineer employed by toyota.

 

[Douglas S]

There is a japanese research paper on cavitation in the bearing shells of a 6 cylinder diesel engine. One of the authors of the paper is an engineer employed by toyota.

I would hardly call that definitive.

 

[Dougal]

I would hardly call that definitive.

Call it what you like. These engines have a specific problem that requires periodic shell replacement.

 

[gerg]

That is a kewl find Doug. I have suspected cavitation for a long time on these motors. I spent a bit of time last night reading about crank whirl and certain frequencies some unfortunate engines can develop to varying degrees. Can whirl occur on rod bearings as well? Is it like something that affects the entire crank?

One of the many non drastic small scale solutions to address whirl relatd cavitation was to run tighter bearing tolerances, cooler oil, and different viscosity oil (lighter but still with as high or higher film strength),and depending if it is isolated to specific bearings on the crank...as in BEBs... You can tear drop some bearing journals to bias oil flow to the ends of the crank and feed the BEBs more oil. Some even go so far as to groove the bearing to increase the bearing load as most whirl and cavitation seems to happen at part and light loads, but I wouldn't be the first one to try that out on my truck I must admit.

I would think that if the bearings were moly coated to tighten up tolerances a bit... Some only need as much as 8thou, and run say amsoil series 3000 5-30 oil, which has a lower viscosity index of regular syn diesel oils but still has great film strength, and run an external oil cooler as well, might lessen this phenomenon. If I get a 1hdt I will be implementing this.
Certainly getting contaminants out of the oil is also a priority. Systems to remove fuel and antifreeze contaminants are expensive. Water is easy.


The marine 15-40 amsoil diesel has similar properties to the series 3000, but not quite as good.

 

[Dougal]

I also suspect the Australians have the biggest problem due to the amount of time they spend at constant speed and load.
In comparison New Zealand vehicles would rarely see more than half an hour of the same rpm and load due to hills and corners.

 

[roscoFJ73]

Its got to be related to the added power of the 1HD T as it is rare on a 1HZ. 1HZs get really hammered in the workplace and I have driven mine at 120klm/h for long periods with loads and the bearings have been perfect at 200000klm.
I really can not see a valid reason related to the type of oil used

1HD T owners will just have to get used to changing them every 100k, or drive them at 1HZ speed LOL.

 

[Douglas S]

Call it what you like. These engines have a specific problem that requires periodic shell replacement.

I'll call it hardly definitive. An obscure paper that you did not provide a link to that mentions 6cyl engines (the 1HD-T must the only one ever made!) and may have had a Toyota engineer help write it. Please.

Doesn't mean you're wrong, you may very well be right. You'll have to do better than that though.

 

[roscoFJ73]

I'll call it hardly definitive. An obscure paper that you did not provide a link to that mentions 6cyl engines (the 1HD-T must the only one ever made!) and may have had a Toyota engineer help write it. Please.

Doesn't mean you're wrong, you may very well be right. You'll have to do better than that though.

I cant think of any other 6cyl Japanese diesel that suffers from bearing delamination. It kind of fits in with what a couple of old mechanics here told me.

 

[gerg]

I don't think he has to do better at all. The 1hdt speaks for itself. The paper is just another piece of the puzzle. There is something very wrong with that engine in its stock form. However, if you change key components of it, you might mitigate this destructive habit it has.

I only thought of the 5-30 as it has some awesome properties in itself, but would also be less viscous to allow for tighter bearing tolerances. Tighter tolerances lessen the crank whirl effect. The fact that the 5-30 had superb film strength is also to fight the whirl in itself as it challenges the film strength tremendously. Specifically at the 5 o'clock position in that bearing pic. The 5-30 also has really low shear viscosity allowing it to run inherently lower bearing temps which in turn also helps maintain the film integrity. It is just overall a better oil. It creates less heat all the time, yet has superb film strength? What more do you want?

Whirl creates such high isolated bearing temps that it can cause cavitation of contaminants. Lower oil temps might lessen the cavitation in itself. I suspect fuel personally as the 1hdt likes to run dirty at idle. Just a thought.

If it does suffer whirl, oil changes mean nothing. The motor would break the film on the first drive. What Dougal said makes since about load in New Zealand vs Aus. In mountain country your rarely part load which is where the whirl develops. It is specific to bearing load, that's why some engineers choose to remove bearing material to run higher loads all the time. It's sort of counterintuitive, but neat.

 

[Hulsty]

I thought it was common knowledge the 1HDT had to get the BEB done every 100K friends have done it to all 3 of theirs religiously after the first one let go at 140K

 

[gerg]

It is common knowledge. However, is not normal for a modern engine.

 

[Gareth]

Got pictures of the other shells?

The rest look the same. That was the worst, though not by much.

 

[Gareth]

What oil was used?

Not sure. At the time that picture was taken I'd only had the truck for ~15k kms.

 

[Gareth]

Without having the shells in hand, the spot in the center looks like debris on the backside of the shell.
The other wear looks to be fatigue wear.

Red antifreeze mixed with oil will do similar damage.
Just about looks like shells from an engine I am fixing that had coolant mixed with the oil for an extended period.

I'm not sure what you mean by "debris on the backside of the shell" There was nothing trapped between the bearing and the rod.

There is no coolant in the oil either. The motor is in great shape, it's spotless inside, no sludge and 35psi oil pressure at hot idle.

I posted these pictures after seeing a few people on here putting forth the idea that the fault was with the oem bearings, and that replacing them was the cure for this problem.