1HDT - help with diagnosing oil in coolant (1 Viewer)

[nickolai]

Hi All. I have a 1994 HDJ81 with a 1HDT. Currently it has done 375,000km. I have owned it since 352,000. I’m getting (what looks like) oil on my rad cap and coolant droplets in the intake.

Some backstory. I picked this truck up for a great deal, much, much less than ‘going rate’ here, knowing that it needed a bit of love. I drove it for a bit to get used to it, and work out what I wanted/needed to do. At 360,000 it got water pump, timing belt, hoses, heater valve, thermostat and a new radiator (original was brittle). It got a really good flush and refilled with new coolant. This was all just before Christmas 2018.

Around 365,000 km I had some odd behaviour, in that it seemed like I was loosing coolant. I also thought that I was pushing coolant into the overflow, but it turned out that the pickup tube had fallen off. I also noted that the cap didn’t seal very well so I replaced the overflow bottle, it’s cap, it’s hose and put a new radiator cap on too.

Fast forward to now, and I have what looks like oil on the radiator cap. I also have coolant droplets in the intake tube and in my oil catch can.

I need some help in working through possible theories. These are (in order of seriousness)
Cracked block
Cracked head + gasket gone
Gasket gone
Oil cooler leaking
Turbo housing cracked and oil and coolant mixing.

Is a head gasket / head job in my future?
Is it possible for a CT26 to fail and let coolant and oil mix?

Is there something else I should look for?

Other points:
It does not get hot / overheat even loaded, up hill at 80Km/h
I’m losing maybe 10mm of coolant from the overflow over 4-5,000km
No milky oil, no coolant when in oil noted when doing last oil change (374,000)
I have oil staining in the overflow
It is not pushing out coolant
Exhaust doesn’t smell of coolant
Makes good power
Needs a rear main seal and pan reseal
From cold start I get a quick puff of black smoke and then clear.

 

[VX 12HT]

generally if its forcing coolant out under pressure its a head gasket that does not look good. Oily residue in the coolant is not a good sign you need a good cruiser mechanic to diagnose maybe what is going on including a TK test or some the other reasons you listed it could be.

 

[nickolai]

I have a TK tester and compression tester on order. I won’t be able to do the tests until next week however.

I understand that a TK test isn’t super sensitive for diesels though?

 

[roscoFJ73]

I would check the oil cooler and then pull the head off. If its a head problem I would consider rebuilding the whole engine at 375k.

 

[nickolai]

I would check the oil cooler and then pull the head off. If its a head problem I would consider rebuilding the whole engine at 375k.

Cheers. Injector pump needs to come out to get the oil cooler cover off?

 

[roscoFJ73]

Cheers. Injector pump needs to come out to get the oil cooler cover off?

I forget, but I know there is not much room down there. The FSM would probably tell you.

Do your radiator hoses stay hard all night or have more pressure than normal?

 

[nickolai]

I forget, but I know there is not much room down there. The FSM would probably tell you.

Do your radiator hoses stay hard all night or have more pressure than normal?

Cheers. FSM is vague on the process but I’d be pulling the engine anyway to sort out the rear main and the pan - and incase it was rebuild time.

Hoses are soft when dead cold in the morning, they build normal pressure even over a long highway, but they don’t go rock hard or anything like that.

 

[Feistl]

This isn’t related to the problem, but is the aircon working and do you know how old the clutch is? (Assuming manual?).

Reason I ask is if the aircon is stuffed then removing the front condenser and pulling the engine out is actually a pretty straight forward job. While the engine is out you can check the oil cooler, change the BEBs, do the clutch/rear main seal as they’ll all be due. If the oil cooler doesn’t look like the suspect then it’s probably a case of pulling the head off and get it crack tested and the block checked.

The big problem though is how far do you go with the rebuild? It isn’t a cheap process once you get started and it’s easy to fall into the “while I’m at it” approach (I’m literally caught in that trap now)

 

[nickolai]

This isn’t related to the problem, but is the aircon working and do you know how old the clutch is? (Assuming manual?).

Reason I ask is if the aircon is stuffed then removing the front condenser and pulling the engine out is actually a pretty straight forward job. While the engine is out you can check the oil cooler, change the BEBs, do the clutch/rear main seal as they’ll all be due. If the oil cooler doesn’t look like the suspect then it’s probably a case of pulling the head off and get it crack tested and the block checked.

The big problem though is how far do you go with the rebuild? It isn’t a cheap process once you get started and it’s easy to fall into the “while I’m at it” approach (I’m literally caught in that trap now)

I’m Auto, but this is pretty much what I’m thinking. My AC is cold but it’s cheap to regas given the other stuff being done.

My plan (at the moment), is:
Compression test
TK test
Motor out
Check oil cooler
Rear main, BEB, oil pan reseal
If compression test and TK indicated an issue then pull head, have that checked etc.

 

[wapitimud]

???

I'm not familiar with this engine, as I only know the 1HZ and Perkins diesels. Once you do other basic troubleshooting, and eliminate other factors, it's most likely you have either cracked head or hopefully failed head gasket, although it is a Toyota and not a Honda You'll need to pull the head and send it to machine shop for crack testing, unless the gasket is obviously failed alone.

You could even have an internal-cracked block for coolant and oil to mix. I've never seen that though without cylinder problems. I would be thinking of replacement rather than rebuild if troubleshooting leads that way.

The engine doesn't need to be pulled for pulling the head on my 1HZ. Drain all coolant and oil, and disconnect battery. Follow FSM for turbo, camshaft, and head removal in-frame.

If you know you're doing bottom end too, yes, pull the engine. This hasn't been established, has it? Good power/ compression before this problem started? Although you have higher mileage, I don't see cause-effect of pulling the engine at this point.

 

[wapitimud]

Did you pull the head off?