'77 BJ40 B diesel suffered coolant freeze (1 Viewer)

[Aaroneous]

I'm new to the Toyota world (and the diesel world), but have been a long time shade-tree mechanic so I like to think I'm pretty competent. I took on a project for my cousins to get their '77 BJ40 kicking again in two stages... first, diagnose and repair the existing B motor and second, install a 13B-T in its place to make it more competent at altitude here in Colorado. I will probably start a build thread when we get to the 2nd part, but I wanted to see if there were some opinions on diagnosing the B so we know what's really going on in there before we remove it.

The backstory...

BJ40

• Aaroneous
• Oct 29, 2016

They bought this truck a year or so ago from Texas, and had it shipped up to Chicago. It ran fine in TX, but after ~120 miles in cold weather, they had a fairly catastrophic failure. A few freeze plugs blew out and it bled out of coolant and started hemorrhaging oil from the passenger side. They took it to a local mechanic (Midas, I think) for an opinion and they put new freeze plugs in it but weren't able to stop the oil leak. They called it a cracked block and unrepairable (enter the 13B-T plan).

They dropped it off at my shop yesterday and I took a quick look at it and saw this...

Cracked oil cooler case

• Aaroneous
• Oct 29, 2016

My gut tells me the owner from TX had filled the coolant system with water, and when everything froze in Chicago, it blew the freeze plugs (coolant drop) and cracked the oil cooler case causing the oil bleed. On the outside of the motor, there is no evidence of a cracked block unless a gallery wall ruptured. I haven't drained any fluid to see if there's coolant in the oil.

So I'm curious... Is my logic in the ballpark? Is the pictured cracked housing even an oil cooler case? I was under the impression that if the B motors had one that it was externally mounted and coolant ran through from the front of the motor (thermostat housing?). However, the 3B seems to list it as the oil cooler case. See below...

Oil cooler breakdown

• Aaroneous
• Oct 29, 2016

Thanks in advance! Looking forward to getting into this project.

 

[Rock40]

Yes, that is an external oil cooler assembly which is cooled by circulated coolant. My guess is you're on the right track with this. If Midas didn't screw up the freeze plug install, then I'd try to source up a used cooler and go from there. You might be lucky and NOT have a cracked block however if it froze hard enough to blow out the freeze plugs and crack the cooler than it was frozen very, very hard.

If it was me, I'd replace the cooler, change the oil, mix the correct the anti-freeze and do a compression test.

 

[lostmarbles]

That engine can't be a 1977 because that oil cooler is post-Aug1980.

If you want to know for sure if it is a 3B or B just look at the engine block here and you should see:

 

[Aaroneous]

Thanks for the feedback, guys. I am sure it's a B block, but I was confused by the 3B style cooler housing as well. I have started looking around for replacement covers but am pretty shocked by some of the prices... Mostly around $650. Seems about $450 too much, but I guess that's what happens when they don't make them anymore. It feels like a tough sell to propose spending $650 on a gamble for whether or not there's further damage inside. Might end up pulling it out and selling it as is and go forward with the 13BT in that case.

A pic of the block stamp

Block stamp - it's a B!

• Aaroneous
• Oct 31, 2016

 

[Aaroneous]

Would it be worth considering TIG welding the crack up in order to do a compression test? That would be a free way to figure out if there's any internal damage. If it tests out OK, drop the coin on the replacement cover.

 

[cruisedeisel]

I would pull the head off and do the precups. I froze my block and 24 hours later it dropped a pre-cup in the #4 cylinder and destroyed my engine. If you choose to run that engine that is.

 

[Rock40]

You can try TIG welding the cooler, it's junk anyway at this point. I thing with how badly it's broken, you're going to have a very hard time keeping the sealing surface straight/aligned. It's worth a shot though.

 

[Aaroneous]

I would pull the head off and do the precups. I froze my block and 24 hours later it dropped a pre-cup in the #4 cylinder and destroyed my engine. If you choose to run that engine that is.

This is really good info, and I think when we sell the existing B motor we will disclose that it needs a rebuild. At this point, I just want to know if the engine is junk or not.

You can try TIG welding the cooler, it's junk anyway at this point. I thing with how badly it's broken, you're going to have a very hard time keeping the sealing surface straight/aligned. It's worth a shot though.

I'm thinking maybe JB weld will get me past the diagnosis and compression test. I found a good option for a reasonable price for replacing the housing, but I want to keep the diagnosis cost as low as possible since we are planning to replace the engine with the 13B-T, anyway.

 

[cruisedeisel]

If your going the 13bt route, just sell or give it away. This is just a "b" engine is it not? Hard to come by for parts

 

[Aaroneous]

If your going the 13bt route, just sell or give it away. This is just a "b" engine is it not? Hard to come by for parts

Yup, it's just a "B", but if it has some value and I don't have to spend any money to figure that out, I'd love to be able to price it appropriately and sell it with confidence that it's not just a paper weight.

 

[cruisedeisel]

Considering some ones going to have to drop a minimum of $1000 on that engine. I personally would give it away. The injection pump is the only thing worth anything. Might be able to get up to 500 max for it but that's pushing it. Might take a year to sell it?

I bet it would take awhile to give it away. No offence!

 

[Aaroneous]

Considering some ones going to have to drop a minimum of $1000 on that engine. I personally would give it away. The injection pump is the only thing worth anything. Might be able to get up to 500 max for it but that's pushing it. Might take a year to sell it?

I bet it would take awhile to give it away. No offence!

None taken! We are totally fine with stripping it and taking it to the scrap yard (that was our plan), I just thought it would be worth spending some time finding out if it would run again. There's a likely scenario where we spend time only to find it's scrap, and it sounds like there's a good chance that internals are damaged in addition to the externally visible damage, so maybe just pull it and move on is a reasonable option.

Curious if anyone feels strongly that it's worth attempting a fix?

 

[Rock40]

I'd still do what I mentioned above. It will cost very little besides effort and time. The internals may be fine but you won't know until you put a little time in it. If the "B" is good, you'll be a lot closer to driving your truck again than if you have to do the swap.

 

[lostmarbles]

The 2977cc B-engine isn't ideal if you run with a lot of weight, regularly tow heavy trailers, or like doing rooster-tails in sand dunes ... but I've always been content with it. So I don't consider a 2977cc B-engine worthless by any means.

And just take a look how much trouble people have in getting "replacement injector lines" for example. This shows your engine has value to someone like me (when I had my BJ40) simply "for spare parts".

In fact I bought a spare engine for my BJ40 with the idea of swapping it in at some stage to recondition the existing one. It's still in my garage and I've never run it since buying it (and I have no idea of its history). I still intend to fire up this engine though (when I get the spare time) because I do want to sell it with some idea of it's internal condition.

So on this basis, I would like to say you should try and fix that oil cooler.

But the trouble is, I don't see how you can do so without buying a new second-hand casing and the search for that could be very difficult.

Looking at this pic....

... I think the crack must pass straight through an oil passageway in the casing meaning it will be leaking into the coolant area inside as well and will be very hard to repair.

So I think you probably have to just sell the engine as is .. as a "spares engine".

My spare engine is complete with all the EDIC system, starter and alternator - which are all "original" to the BJ40 model it originally was fitted to.. So that to me means it has "significant value overall" to anyone wanting spares.

So depending on how much similarly "useable/saleable components" will be left on yours, your engine may have "significant value" or "almost no value" I think.

(No-one is going to want to store a whole engine if the only thing they can see that they may want in the future is the injector lines.)

Cheers - Tom

 

[Aaroneous]

Thanks so much for the feedback, guys. I am going to go ahead and remove and inspect the oil cooler while we search for a replacement. Looking at the B engine manual, it suggests that you need a Toyota SST to remove the cover. Is this something I should try to source before I open it up or is there an alternative tool that will work?

Special service tool required for oil cooler removal/replacement?

• Aaroneous
• Nov 6, 2016

Manual suggests SST 09313-30021. Required? Potential substitute? Where to get?

 

[lostmarbles]

No. I wouldn't bother with the SST.. If my existing toolkit couldn't do what it does then I'd make something that would..

I see Toyota calls that a "detent ball plug socket"

 

[Aaroneous]

Attempting to get things squared away today - new oil cooler assembly arrived and is all cleaned up and ready to go. I searched around and found a range of opinions on whether or not to use RTV on paper gaskets for the oil cooler housing and the oil filter bracket. In the past, I have smeared some Ultra Black on both mating surfaces for parts like this but, if the paper gasket is sufficient, I don't want to create leaks or potentially pull dried RTV into the coolant or oil systems. Shop manual does not specify, either. Thoughts?

 

[Aaroneous]

Welp, the oil cooler replacement went well. Removal and installation were maybe 45 minutes, the other 3 hours were spent prepping mating surfaces. Had to remove the exhaust from the manifold flange in order to get the cooler off the rear mounting stud, otherwise it was exactly as the manual suggested. For reference, the SST above is actually a 6mm allen. I ended up smearing Permatex Ultra Black RTV on mating surfaces and gaskets (right or wrong).

The unfortunate news came when I tried to refill the coolant... Filling the radiator drained coolant directly into the oil pan. Looks like this engine is toast - going to sell as a spare and start prepping for the 13B-T swap. I'll start a separate thread for that process.

Thanks very much for the help through this, it's really great to have a group of knowledgable folks willing to share wisdom!

 

[lostmarbles]

That engine must have suffered a really severe coolant-freeze!

(I suspect it probably froze without any antifreeze at all in the coolant.)

Sorry it didn't turn out better for you but at least you now have a better idea of the extent of the damage.