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interesting read on ACL bearings

Interesting, I've just bought another 12v so I think I might invest in a set.

Put ACL in the other.
 
Just partially read that and a couple of things stand out. First, they now (Morris's oils that is) recommend two grades of oil for the 1HD-T (10W-30 and I would have to check but I think 5W-30). Also my original bearings changed after 130,000 miles with the first 60 spent in Japan, were in superb condition. Didn't need changing. Others have reported the same. Lastly, the 1HD-FT is (correct me if I'm wrong here) basically the same engine from the head down? I believe they rarely have BEB failure.

Could it be that the uprated power of the 1HD-FT helps eliminate the problem? Against this theory as the main reason, I believe Toyota now specify the shells from the 1HD-FT for the 1HD-T, which kind of indicates it is or was suspected to be bearing composition.
Maybe it's a combination of the two or of many factors (more likely). Could driving style help. I always run mine hard where I can based in hearing that diesels thrive on being thrashed. So far so good.
 
I replaced mine around 184,000 miles, now showing about 256,000?

I had a read through many posts about the BEB's being a problem when I did mine, but there was no conclusion as to where to lay the blame.

I noted cavitation was mentioned allowing air into the oiling system, I did mention only recently that the oil pressure can drop drastically (albeit momentarily) if the level is only down by a small amount, this along with usage that results in oil surge.

This will not be picked up by the driver as the oil pressure gauge is slow to react, mine has an oil pressure light/buzzer so it was the sound that brought it to my attention, the light not being noticed as I was too busy watching where I was going.

This however does not explain why the 24v version does not suffer unless the oiling system is different to suit the different head?

Does the head retain less oil during running, is the sump baffled at all on the 24v version? I am not convinced the oil type is to blame, perhaps it has something to do with the flame front produced by the 12v is different to the later engine?

So many questions, so few answers.

Regards

Dave
 
That's right Dave....few answers.

The crankshaft design with force fed oil through the bearings has been out for at least 100 years and has not changed. Thin walled bearings came in use for cars after the war but the design of the system was not altered.

Up until the 70's big ends did not last very long. After that hardened and polished crank pins and better oil meant that big ends would last the life of the car.

With regard to big end failure on the 12 valve engine it's metal to metal contact in the same old place on the bearing as years ago. Now once the bearing has started rattling people say you can save the crank pins if caught in time. Out comes the micrometer and all appears within tolerance but has the surface of the pin lost it's polish and caused new shells not to last long ?

Does the 12 valve engine use graded shells from the factory ? The 24 valve engine does. 1. Why grade the shells ? Is it because it's cheaper to machine the block and crank roughly then you only have to make the shells accurately ? 2. Why grade the shells ? The answer is to obtain the correct running clearance irrespective of the answer to 1. above. Too bigger gap and the pin will thrash about in the bearing. To small a gap and there will not be sufficient oil flow ?

The M1 motorway was opened in 1959 and ran straight past the Aston Martin factory. What would you do as a test driver ? They went straight onto the M1 together with new owners . There was no speed limit and all of a sudden big end failure became common. I quote from the workshop manual written soon afterwards re:- main bearings "In order to ensure that the running clearance of the main bearings is maintained within close limits, a range of bearings with different wall thicknesses has been introduced". Big end bearings were not graded but it is obvious that these relied on "tight" main bearings. Main bearing running clearance .0015" for standard DB4 engine and .001" for the DB4 Gt. Oil pressure was also increased. Former hot running at 2000 rpm was 75 psi then 120 psi. That was what was on the gauges anyway. When I started my first DB4 GT engine the oil needle went full scale deflection to 170 psi.

My 24 valve shells have a hard surface. you can't scratch it with your finger nail Are the 12's like this ? Years ago you could scratch the surface of the lead indium coating with your finger nail.

Perhaps the answer to the 12 valve beb failure lies with the main bearings ? Perhaps it was just a bad batch of shells like 2 million air bags ?
 
I have been building engines like yourself Frank for years, mainly for competition use, I always requested the cranks to be polished and tuftrided, never had any failures...ever.

Yes the M1 was opened the year I was born....god am I really that old?

The Toyota 12 valve was designed and built much later, and given Toyota's build quality I am surprised this has been an issue. I note that some countries that had engines fail were replaced by Mr T under warranty. My research indicates this was more prevalent in Australia, the mileages being greater there per year than in many other countries.

I decided with my engine I would run the ACL bearings for 100,000 miles and then change them regardless of condition, the job is not that difficult. The 12v does have graded bearings, the theory being you mic the crank and choose the next nearest OE size, the 'one size fits all' ACL version being a compromise between the smallest expected clearance to the largest. I plastigauged all of mine and they were all 'within spec'. The spec was quite generous IIRC, the diesel engines being subject to lower rpm ranges would allow for this.

The OE bearings on mine had started to delaminate, this indicated there may have been many possible causes, poor manufacturing technique the outer lead indium not adhering to the steel shell backing? Localised overheating at the rod journal, insufficient oil flow (related localised overheating), even the timing of the engine could have had an effect.

Nothing can be done if the rod lets go, and no one has actually come up with a factual reason backed with evidence as to when that will happen, I guess we all know there is a question mark over bearing reliability on the 12v, knowing how I am stupid anal over oil changes, it will be interesting to see the bearing conditions on mine when the time comes around.

Regards

Dave
 
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I replaced the BEBs on my 1995 1HZ at about 230k km and they were a bit scored in places but no delamination or other things like the disaster photos posted on this forum.

My oil pressure relatively high when cold at about 3.5 bar (50 psi) and in the very cold weather -25C it was up to 4.5 bar (63 psi) on start-up.

However, when at running temp, it falls to 2 bar (28 psi) at modest running speed (1800 rpm) and down to 1 bar (14 psi) at idle.

I don't worry about it, there's no untoward noises from anything.

I've always been under the impression that it's the oil flow (or restriction) through the mains that regulates the oil pressure, but that may be an out-of-date concept after reading Frank's post above.

Surely, very high oil pressure would indicate a high restriction, thus a lower volume of flow, so I'm guessing that there's a compromise point where the flow is sufficient whilst maintaining a suitably pressurized cushion to keep metal from touching metal during operation...

Whatever, but I'm approaching 400 k km now and I'm wondering if I should change them again? I used Mr T calibrated shells last time, not ACLs or another brand.

But because there was so little damage showing on the 230 k km BEBs, I'm a bit reluctant to do them again.

I know, I know, better safe than sorry, it's ringing in my head, but it's not an HDJ and I'm also paranoid about changing the oil and Mr T filter at 10 k km, so what to do...

Decisions, decisions....
 
Being a different engine again Clive this shows the 12v turbo being on it's own in this respect. It could also add a little credence to my thoughts with regards to the way the flame front builds? Perhaps the turbo is increasing the load at higher revolutions, TBH I would be happy to hear any thoughts as to the cause.

Regards

Dave
 
I replaced the BEBs on my 1995 1HZ at about 230k km and they were a bit scored in places but no delamination or other things like the disaster photos posted on this forum.

My oil pressure relatively high when cold at about 3.5 bar (50 psi) and in the very cold weather -25C it was up to 4.5 bar (63 psi) on start-up.

However, when at running temp, it falls to 2 bar (28 psi) at modest running speed (1800 rpm) and down to 1 bar (14 psi) at idle.

I don't worry about it, there's no untoward noises from anything.

I've always been under the impression that it's the oil flow (or restriction) through the mains that regulates the oil pressure, but that may be an out-of-date concept after reading Frank's post above.

Surely, very high oil pressure would indicate a high restriction, thus a lower volume of flow, so I'm guessing that there's a compromise point where the flow is sufficient whilst maintaining a suitably pressurized cushion to keep metal from touching metal during operation...

Whatever, but I'm approaching 400 k km now and I'm wondering if I should change them again? I used Mr T calibrated shells last time, not ACLs or another brand.

But because there was so little damage showing on the 230 k km BEBs, I'm a bit reluctant to do them again.

I know, I know, better safe than sorry, it's ringing in my head, but it's not an HDJ and I'm also paranoid about changing the oil and Mr T filter at 10 k km, so what to do...

Decisions, decisions....
It is mentioned in the thread that there isnt a problem with the naturally aspirated engine. I changed mine after hearing what i believed to be a slight rattle under power. Im familiar with the noise after having four 16 valve cavalier engines let go on me when i used to ge everywhere at 100mph..

Ive got over 100000 miles on the taiho bearings now will be interesting to see how there holding up.
 
Whatever the cause, it's comforting that it's an easy "service" to replace them. I didn't do mine myself, but my trusted workshop did it for me in about 3 hours.

They're familiar with the 80 series and very enthusiastic about them. Four of the workshop guys there have landcruisers, a 70, 2 x 80s and a hundee, so they know their stuff.

With the labour being cheap, the most expensive bit is the parts, but I (and they) insist on fitting Mr T stuff.
 
You've got me thinking Clive, is there anything I need doing while I'm with you that I could get your guys to do. They sound like Romanian versions of Trevor and Ed…x2. :)
 
Dave isn't it the bottom bearing the con rod that goes irrespective of which engine ? I've never understood this as this as, in my mind, this is not the compressed end of the rod taking the explosion from the combustion chamber.
 
Two theories here Frank, the 'push' of the compression stroke 'may' be softer against the top bearing, the lower bearing having to suffer the sudden change in direction brought about by centrifugal force.

The spanner in the works is the timing of the engine, if the timing is a little advanced then the push of compression is trying to reverse the upwards stroke of con rod, so you would have thought the upper bearing would be the first to wear.

There are things that have an effect for example, the con rod cap has less metal or bulk to shed heat, also bearing crush can (assuming the rod eye has not been resized) can mean the cap end of the rod does not apply an even force across the bearing face.

TBH normally most of the above would not be noted in an every day use engine but, if there is evidence that the shell in the bearing cap is the one delaminating first, or appears to suffered the most damage, then perhaps heat is the root cause of starting the delaminating process, perhaps aggravating an already faulty bearing shell design?

This is all speculation but may be pertinent to the discussion?

regards

Dave
 
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if i was to pick up a 12v, any idea on cost to do the beb swap?
 
It took me 6 hours to strip them all out, measure them with plastigauge, and refit. Others are quicker.
 
I would say it took me at least that. Probably 8 hrs with a break overnight to let the oil pour out all over the floor. :angry-screaming: Which added a good 1/2hr of cleaning up. :icon-rolleyes:
 
This^^^^^^^^^^^^^

The classic I have found when replacing them is you leave the car overnight with the sump plug out, remove the sump safe in the knowledge that there is no more oil to come. Then release the oil pickup pipe and as you remove it air runs up into the pump and then another cupful of liquid gold comes out!!:mad:

regards

Dave
 
You've got me thinking Clive, is there anything I need doing while I'm with you that I could get your guys to do. They sound like Romanian versions of Trevor and Ed…x2. :)

I guess you could, if you don't mind delaying your homeward trip.

They are a busy workshop, so usually I have to plan work about a week or 10 days ahead, for a slot.

If you do come up with a plan, I'll get you booked in. They're situated on the outskirts of Bucharest, on the opposite side of town to where we live, but I could take, or rather lead you there if you need work done, and you can stay at our apartment while you wait, if it's a day or two job.

Parts generally take a week - 10 days, unless you bring them with you of course, so we'd have to factor all that in.

Anyway, it's doable, as long as you're not tied to time going home.

If it's bodywork, panels and/or painting, then it's a different workshop, and they operate on a similar basis, depending on the job.

A full re-spray is a good weeks' work allowing for dismantling, prep and reassembly.

When he did the welding on the rear quarters, it took him 2 days.

Let me know Rich, OK?
 
Thanks Clive, I was really only thinking out loud as there's nothing I wouldn't tackle myself, and I've had work done before on a vehicle that was needed to get me home twice ending in train journeys and much extra expense. Appreciate the thought though. :)
 
If you change the BEB's, do you order all the different ones? Because I was told when you take them out there's a number on them regarding the thickness, and you need to be sure to replace them by the same thickness.
 
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