Overheating issues (1 Viewer)

[benmgsr]

Gday all,

Ive got a 1986 BJ74 landcruiser, 13bt turbo diesel.

It has started overheating after about 10 - 20 mins of driving.

The thermostat seem to work fine (i boiled it up in a pot)

I took the thermostat out and ran it for 20 mins driving and it barely got off cold... but as soon as it goes back in the problem is there...

I will buy a new thermo, but i still dont think that is the problem...

any ideas?

Thanks

 

[ForealBoreal]

waterpump.

my buddies did the exact same thing the other day.

 

[benmgsr]

that's what i was thinking, thanks

 

[Phil in BC]

Cracked head gasket?

 

[Cruiser70]

radiator full of mud....possibly..

 

[roscoFJ73]

that's what i was thinking, thanks

Unless the impeller has fallen off,I cant see how a water pump would stop pumping.
Its easy to check by removing the top hose and watch for coolant coming out of the head.
Its a lot of work to replace a pump especially if that doesn't fix it.

I always start with a new radiator cap and see if it builds pressure.
You should be able to feel warm water coming out of the top hose after 5-10 minutes if the thermo is working.
The warmth is quite sudden once it opens

 

[Radd Cruisers]

There are lots of things to look at to solve overheating problems. The first and most common problem is a bad radiator cap, so check that first. The rad needs to build pressure to prevent overheating (also check for pressure/coolant leaks in other parts of the system).

If your truck is JDM, then the radiator is most likely plugged up. It seems to be the case with many of the JDMs that I come into contact with that the cooling systems are in poor shape.

The radiator and thermostatic fan work in harmony with one another, the fan won't engage properly if there is not hot air moving over the rad to engage the thermostat/fan, and there won't be any hot water moving through the rad (at least not enough in the area that matters - which is mostly the central portion) if it's blocked or partially blocked.

The other thing about a blocked or partially blocked rad is that they don't conduct heat as well as a clean rad.

Further, make sure that your alternator/fan belt is sufficiently tight.

And, check that there are no obstructions in front of your grille.



hth,

John

 

[benmgsr]

OK, thanks for all your replys, but i am still having issues.

I have replaced the water pump, the radiator cap and the thermostat. The radiator has also been cleaned and flushed.

I put this all together and took it for a run. (It has always run at about 1/4 of the way up the temp guage)
Started off fine, then slowly raised to 3/4 and then dropped to just below half. Stayed there for approx a 30 min drive.

I got out of the ca upon arrival and walked past the front and heard bubbling, opened the bonnet and found the overflow bottle full and bubbling.

Any ideas?
I think i, going to take it to a rediator joint and get them to test it....
Air lock?
Head gasket? (keeping in mind there is no water in oil, oil in water or water out exhaust.).....

 

[roscoFJ73]

OK, thanks for all your replys, but i am still having issues.

I have replaced the water pump, the radiator cap and the thermostat. The radiator has also been cleaned and flushed.

...

How was the radiator cleaned and flushed?
You really need to have the top and bottom tanks removed and the cores rodded so you can see from one end to another.

 

[benmgsr]

I'm not sure, it had been cleaned by the shop in August, and i just took it back to them to have it checked again.... they said they flow/pressure tested it and it was fine.

 

[David*BJ70]

I have replaced the water pump, the radiator cap and the thermostat. The radiator has also been cleaned and flushed.

That look like my previous grocery list ... before I've pull the head a make a head gasket job...

I got out of the ca upon arrival and walked past the front and heard bubbling, opened the bonnet and found the overflow bottle full and bubbling.

Any ideas?
I think i, going to take it to a rediator joint and get them to test it....
Air lock?
Head gasket? (keeping in mind there is no water in oil, oil in water or water out exhaust.).....

Pressure from the combustion pushing air into the coolant system and the only way to get out is flushing all the coolant and finaly make your engine overheating. There is some thread about that in the diesel forum.

I'm sorry for you.

 

[roscoFJ73]

I'm not sure, it had been cleaned by the shop in August, and i just took it back to them to have it checked again.... they said they flow/pressure tested it and it was fine.

Assuming it was full of crud ,you cannot really be certain the cores are not fully unblocked without rodding them.
I cant imagine any amount of water flowing through the radiator would clean it out properly.
You might still get a good flow/pressure result with 20% of the cores blocked.

 

[cicak]

if the radiator shop did not tell you your radiator was full of crud or clean when you had it cleaned then I suspect they did not clean it corrrectly - did they do reverse flush etc. ITs made a huge difference to two of my trucks in the last 1 month already.

Can we assume your air cond radiator in front of the radiator is clean also?

do you have front mount intercooler?

That situation sounds like a head gasket has gone.

WHen you check it when it gets hot is the water flowing into the overflow continuously or in spurts?

 

[scuirer]

Water temperature issues

My '85 BJ70/3B had similar issues. While driving you glance down at the gauges leading to a heart attack because the water temp. gauge is pegged out. Totally unpredictable - could be on a steep hill after driving all day, or pulling out of a parking spot from cold. Closer examination revealed that after pegging out, within a few seconds (2 or 3) it returned to the correct reading. The sender was the problem. The entire cover had broken off the sensor. The first replacement was marked and set for 28 ohm resistance, and after about 6 months had similar problems. On removal had similar issues to the one replaced: crack around the base of the cover. I replaced it again, so far no repetition of the problem. I did also replace the thermostat, but the original 1985 unit still functions fine. When re-fitting the sensor be extremely cautious not to over tighten.

A TOYOTA specialist mentioned in passing that some gauges were subject to ground fault issues, but that did not seem to be the case with my problem.

 

[Phil in BC]

My bj74 did the same thing, build pressure and blow it out the overflow. I tried the thermostat and everything else we could first, but it did not fix the problem. Turned out to be the head gasket which was the original. Head was fine and once put back together no more overheating.

 

[benmgsr]

gasket

Thanks for all the replies.

Further to the problem:
I took it to a radiator shop and we made sure there were no air locks in the system, ran for ages to warm it up and the thermostat did not open until very late, all with radiator cap off.

Today i ran it full of water with the radiator cap on and it took a while to warm up again and again the thermostat would not open.
Upon grabbing the top radiator hose, i notice it is almost ROCK HARD, but cold.

SO, i concluded that the head gasket must need doing as it is pressurising the cooling system and stopping the thermostat to get adequate water and heat to open.

Damn

 

[roscoFJ73]

Upon grabbing the top radiator hose, i notice it is almost ROCK HARD, but cold.

SO, i concluded that the head gasket must need doing as it is pressurising the cooling system and stopping the thermostat to get adequate water and heat to open.

Damn

I had another vehicle do this. The hoses would still be rock hard in the morning before I started it.
Mine was a cracked head though.

 

[benmgsr]

Yeah, the symptoms are pointing to a headgasket (hopefully) or head... I took it for another drive yesterday, stayed within acceptable temperature range, but used water and was bubbling once i stopped.

I think ill book it in for some work....

 

[benmgsr]

OK fellas, ive had the car back for a week now....
Had a NEW 14bt head put on it. The old one was cracked beyond repair in a number of places and the headgasket was leaking all over the place.

Cost me an arm and a leg, but it works now.

Still a bit worried though... The temp still rises to above half and then drops to just above a quarter and stays there (and this process takes a long time). I'll get them to bleed the coolant system again to be sure it's not that. It doesn't seem to overheat, but i havn't pushed it yet...

Any advice?

 

[Hulsty]

How is your fan clutch? Mine used to rise up in hot weather at higher speeds or climbing a long hill. I put two tubes of silcone oil into the fan clutch and now the temp guage does not move from just below a quarter.