toyota 4 Age con rod bearing problems 2

[bigpaul]

Hi help needed with a run of bearing problems on Toyota 4 age engines, we build a high number of these engines without
problem but we are currently haveing a nightmare with Connecting rod bearings what we have is bearings which show classic fatigue problems but do not have a trail to explain the fatigue
we have used diffrent running clearances lubrication
oil pressure and flow also alternative bearing material
and manufacture even lowering compresion this is over
several engines any help or ideas will be gratefully recived
these failures occur in less than 200 miles.

Big Paul.

 

[toytech]

Are these stock rebuilds? What rod is failing? Toyota bearings or aftermarket? First of second generation ie 3 rib or 7rib blocks any additional information could be usefull.

 

[bigpaul]

hi toy tec these are 7 rib small port comp ratio 11.3
272 duration cams on restricted side draft carbs 30mm
manadtory regulation. bearing used so far standard toyota
acl and clevite and fedral mogal (now no longer avalible)
rod one and two. mostley one.

Big Paul

 

[toytech]

Do they swow any signs of oil starvation or are shells hammered like from detonation. #4 is usually the first one to go with oil starvation. Any coolant contamination? I think I would send out an oil sample for analysis and see if there are any silicates, also left over abrasives from machining could be a culprit. Bearing problems are pretty rare on this engine, the stock rods are fairly robust, but you could always switch to the 4agze rods if they are stretching from revs, they can handle a bit more revs but they are also heavier. The ones in my blown mr2 have lived over 220k miles with daily shifts at 7k and almost twice the stock boost. The trd pump might also be a good upgrade as well as a crank scraper.

 

[strokersix]

Are you running a crankshaft torsional damper on this engine? If so, is it adequate for the job?

Mike

 

[bigpaul]

Hi Guys

Thanks for the replys, but this problem is there in standard
non machined cranks there no sign of particle contamination
ie lack of oil there is also little or no main bearing problem the max revs used is only 8100 the last engine that was pulled showed even cratering on all 4 cylindersand no journal damge.
as to balance they have to use std front damper they
are balanced spot on but it rare to have to do much correction
on any of the components I agree that it a rare problem with
4 age but its becoming an epidemic do any of you guys run the
cranks outside bottom limit. if we are running into a windage problem surely it would be showing on other engines?

we do not now have a technical dept that can help at the bearing manufactures so all that kind of insite has gone

 

[ShaunT]

You could be experiencing some problems with one of two things. First, heavy oil starves motors when clearences are tight. If that is not a problem, then consider consulting with ARP @ 800-826-3045. You may be having a distortion problem from bolt stretch/ preload.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

 

[bigpaul]

Thanks for the reply Shaun we have tried both synthetic and mineral oil we also have used standard and arp bolts tightened to there spec also tried change of houseing size
we are pretiy show its some kind of oil problem but pin pointing what is elusive.

 

[evelrod]

Tough problem. I can't offer much else except to double check the lubrication system for leaks. A small, intermittant air leak can cause all sort of aeration and ultimate bearing failures. Possible that rod side clearance could be off. That alone or in combination with wrong clearance/oil viscisity/air leak/bogus pump, etc.
Like I said, tough problem.

Rod

 

[Retracnic]

As stated before, this is a tough one indeed. I am assuming that you have assembled a multitude of these engines without problem in the past. That being the case, we need to step back and look at it logically. For this problem to have begun occurring suddenly, and appear on multiple engines, something must have changed. This could be with your component selection, engine usage, materials composition or assembly technique.

Bearing fatigue is most commonly caused by some sort of overload condition. Whether it is due to detonation, high combustion chamber pressures, or heavy engine loading during low RPM operation.

The symptoms of bearing fatigue and oil starvation are markedly different. I am having trouble following exactly which is the problem described. Maybe with a better description of the failure, we can get closer to a solution.

In any case, I’d start by doing a comparison between one of your successful builds, and one of the failing ones. Analyze all differences in materials, components, and assembly techniques for possible failure paths.

Good Luck, and keep us posted!

Bryan Carter

 

[RobWard]

This may sound daft, and I'm no engineer, but a friend of mine had a problem (years ago) when his torque wrench was not too accurate, and he overtightened nearly everything on an engine rebuild.
2 lessons:
1) make sure you can trust your tools
2)never lend your torque wrench to someone who'll drop it.


"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[DanT]

fatigue symptom = pitting or craters? pictures here

http://www.glaciervandervell.com/europe/

support/damage/default.htm

full bearing width or toward one edge? ever seen cavitation damage on a pump impeller?

what's your oil temp?

 

[evelrod]

Bryan, right on!

Dan, thanks for the link.

Paul, it is often near impossible to diagnose a bearing failure even when you have the engine in hand. I don't know how to do it but, posting a couple of photos could help. Also some oil temp/pres/flow etc. info.

Rod

 

[strokersix]

I'll ask this again. Is there a torsional harmonic issue at play here? It seems to me that the first bearing is the farthest from the flywheel node and will see the highest imposed loading from first order torsional harmonics.

rod one and two. mostley one.

Mike

 

[toyo]

bigpaul, I'm glad I'm not the only one having those kinds of problems. But mine are with the toyota 3e engine. Same kind of thing as you but not yet with the numbers you're seeing. At this point I'm leaning to a stuck relief valve and that possibly in conjunction with the type of oil filter. I'm thinking that some of the filters are bypassing at lower pressures and letting some foriegn matter thru. anyways I'm spending a lot more time in looking at the gallerys to and from filter/relief valve. We also at the moment have a Subaru forester in at work, which recently had a head gasket done elsewhere and it too has done the same kind of thing except for total destruction of the crank. I dont know if that is any help but I'll be checking to see if you have any success in solving the problem.

 

[enginebob]

BigPaul, did you say it revs to 8100? Thats a bunch. Have you checked for oil starvation at that speed? Who's machining the big ends? Are the rod bores inline? And how about oil pump volume? Are you using a good bore gage to check for round rod ends? Are the upper mains grooved? What does the main journal feed hole look like?
Which bearing in the big end is showing distress? Both rod and cap, or just rod? On assembly how are you checking the clearances?

 

[bigpaul]

Hi Guys thanks for all your posts we have the better
of the problems now, we carried out quite a number of deatail changes from Fliters to oil feed and return.
Paul.