HJ45 Engine Issues (1 Viewer)

Joined
Mar 18, 2008
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Buzzards Bay Area
My 1980 HJ45 suffers from overheating at highway speeds only, around town it runs fine, starts easily, runs smooth, no smoke. But at 55-60MPH it gets compression into the coolant jacket resulting in the expected overpressurization. Eventually I was able to find a headgasket leak towards the fire wall. I decided to replace the headgasket and check the head for trueness and cracking. So into the shop it went.:Mechanic:



All the parts came off happily with ease and the project was running smoothly. As I removed the headbolts I checked the torque on them. (before you all chastise me I have already been lectured by a mechanic telling me not to use a torque wrench for removal), that being said all bolt were in the 90-115 ft/lbs range to break them free with the exception of a cluster of three towards the firewall that were down around 60ft/lbs. It seemed to me that I had found the source of my leaking compression. Unfortunately the final step in removing the head was not as smooth as I would have desired. Once all bolts were removed the head was attached to the lift and tension placed on it.



..nothing budged...I gave it another crank on the lift and I could see the head begin to break free from the block. Telltale coolant beads forming all around the outer edge. I took a break leaving tension on the hoist and started up the usaul BS'ing conversation with a friend in the shop. A minute or so into the conversaion the head popped off the block with more force than desired. As it came up it hit the overhang at the fire wall scaring the life out of us, but otherwise did not seem to do any damage.



After a few moments of looking things over I realised that as the head lifted off and hit the overhang on the firewall it shifted a link on the chain hoist resulting in a downward angle and made contact with the fire ring on the number 4 cylinder sleave.






:(

The head was found to be true, but has cracks between the intake and exhaust valve in each cylinder. The cracks are only visible under magnafluxing. I am not a mechanic, but it does not seem to me that these cracks were the source of my overheating.

Though at this point it seems like the head issues are the least of my problems. Anyone on the list care to give me some guidance on next steps? I assume I need to remove the sleave and replace it.
 
Joined
Mar 4, 2006
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Hyogo Japan
 
 
Remove and replace sleeve. Check the piston, might only need re-ringing. Buy new head.

Not sure which came first the overheating or the cracked head but:

Cracks between the valves on a diesel will most certainly lead to air / fuel / exhaust gas in the coolant. Seen it before.

You only have 12 valves, try it on a 1HD-FT.
 
Joined
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Buzzards Bay Area
Thanks for the input. Can the sleeve be removed from above with the engine in place or do you need to remove the engine to do the work?
 

RufusTheDufus

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The last time I had a sleeve replaced the engine needed to be out of the vehicle. (It wasn't a Toyota diesel engine.)

I have the FSM for the H engine around here somewhere. I'll look to see if there's a section about resleeving the engine. I'd guess that there's machine work and a press involved. Work that most likely needs to be done by a machine shop.
 

rchalmers3

I speak Toyota
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Jun 29, 2007
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Playas de Nosara, Nicoya Peninsula, Costa Rica
 
 
I say the motors coming out 'cause of the snowball effect: You are changing the sleeve, then the pistons and rings, then the rod bearings, then the mains.

You don't think the fire ring can be dressed? Why not clean it up and lay a new gasket over it to be informed about how to proceed?

Rick
 
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I'll probably get ridiculed for saying this, but if it was me I think I'd have a go at fixing that with a mig welder and dremel-type tool. (With a lot of care I think it is do-able.)
 

RufusTheDufus

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I found my H Engine Repair Manual.

The cylinder liner is supposed to protrude above the block a little bit. The spec is .03mm to .12mm. I assume this has something to do with head gasket sealing.

The cylinder liners come unfinished and require boring to match the piston size. There are three different "standard" size pistons used in the H engine. If you need these sizes just ask. I'm lazy and don't want to type them all out if it's not needed. There is also 1mm oversized piston option.

BTW, you will need a press that can put out 11,000 pounds of pressure to get the liner seated fully according to the manual.
 
Joined
Sep 3, 2007
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Longmont, CO
 
 
Wow, there is a bummer. Glad I'm not the only one who opens a can of worms when they take their head off :)

Regarding the cracks between your valves, there are many stories on this site of people running 3B heads with cracks between the valves - my reading on it is that they are often benign. That said, since the HG looks like it got wrecked when pulling the head, you can't know for sure what was the culprit... I might get a pressure test and then take a gamble.

As for the sleeve damage, you should be able to see a line of carbon on your sleeves that indicates the height of the rings when the piston is at TDC, and I'm sure it will be below the damaged area. I would fix the damage, but braver men than me might look differently on it. I disagree with Rufus, however - the sleeve protrusion seems to me to have nothing to do with head gasket sealing. The HGs I've installed fit around the protruding area, and do not touch the top of the sleeve walls.
 

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