Overheating

[Red Oktober]

is there anything that can be done to stop this happening .......

i know about keeping the rad clean etc ...but is there anything else ..

i know the little 2.4 works hard to pull a big truck around ...it is very under-powered (especially on 33" rubber) ..so any ideas are greatful

 

[Rob]

There could be a few things causing it: thermostat, viscous fan, inefficient rad caused by residue on the rad internals and externals. And finally it could be a head gasket or even cracked head... So plenty of things to check.

 

[Red Oktober]

Thanks Rob ... plenty of things it could be then

 

[John_McCartney]

Flow of air to rad not restricted in any way? I nearly seized a Zook engine once by putting four spotlights across the front of the grill then batting down the A11 at - ahem - quite some speed.

 

[Red Oktober]

i've got a pair of 8" spots in front of the grill

I didn't have any overheating issues when we drove over to Romsey and back the other week

 

[wobbly]

If it has just started, might be a simple problem.

A new stat is a good start point.

Any bubbles in the expansion tank etc to check the head.

Theres a lot of obstruction at the front - number plate more so than lamps - theres no airflow underneath as the winch is now there.

Has it been waded - could the rad be blocked with mud?

Cheers

Pete

 

[Paul]

As some know i went out to give a hand on this truck.
When i got there, the water level had been topped up a couple of times on the route by Red to get him to the destination, the expansion tank was empty (but everything inside was stained with a layer of brown sludge) and the level in the engine was below the level of the rad cap which sits on what looks like a remote casting just higher than the engine on the front left hand side of the head. We topped it up and ran with the heaters on and a good deal of air bubbled up through and the level settled down so fitted the rad cap and left it running to check things over. The temp gauge sat at the normal level and over a period of time the expansion tank level gradually rose to about an inch from the top and stayed there. The heaters never got very hot. We switched the engine off and and the level dropped to about half way. The next day Red brought the truck to Lincomb (5 miles) and it had seemed to be ok so he set off for home (see other post.)
The whole engine bay is very clean, the rad is not very obstructed and also appears to be clean. The rad hoses have been off recently as they look new and have new non genuine clips on them. There does not look like there has been any major work to the engine.
Being where we were (guest house car park) there was no way to do any testing, stripping down or testing but it got things going.

 

[Red Oktober]

Thanks for that Paul .... gives a better insight to what happened

when we left the site on sunday the heaters were blowing very hot, .... we left them blowing for quite a good few miles then switched over to the aircon.

today .... they were hot again once the engine had reached it's normal temp

 

[wobbly]

Red sludge sounds like radweld.

The first mention of heaters was that they werent getting hot, then next two they are hot at normal running temp on the dial.

Sticking stat could account for the apparent contradiction - but if that was the case then the expansion tank shouldnt have filled up!

It could have been an airlock - if the oil is not creamy and there are no bubbles in the tank at normal operating temp.

The stat is housed in the housing that Paul mentions - all held in place by 3 bolts and a simple job to remove and check there is one in there - and that it is the correct type with the little bypass hole.

When you say you topped the water up on the journey - do you mean you put water in via the rad cap, or into the expansion tank?

What sort of speed were you running at on the motorway?

Pete

 

[wobbly]

Just an afterthought - is there any sticky fluid in the footwells or the tunnel carpet - do the windows mist up and a sweet smell when you put the heater on?

 

[Red Oktober]

Just an afterthought - is there any sticky fluid in the footwells or the tunnel carpet - do the windows mist up and a sweet smell when you put the heater on?

nope .. nowt happening like that

 

[Red Oktober]

Red sludge sounds like radweld.

The first mention of heaters was that they werent getting hot, then next two they are hot at normal running temp on the dial.

Sticking stat could account for the apparent contradiction - but if that was the case then the expansion tank shouldnt have filled up!

It could have been an airlock - if the oil is not creamy and there are no bubbles in the tank at normal operating temp.

The stat is housed in the housing that Paul mentions - all held in place by 3 bolts and a simple job to remove and check there is one in there - and that it is the correct type with the little bypass hole.

When you say you topped the water up on the journey - do you mean you put water in via the rad cap, or into the expansion tank?

What sort of speed were you running at on the motorway?

Pete

we were running at around the 60 -65 mph mark

the top ups were done through the rad cap.

oil is black ...not creamy or mayo like dipstick was clean too and oil at the correct level
no white smoke ...or any smoke for that mater

 

[jeepmadmike]

I'd move the number plate front the lower grill slots.....

It's worth giving the hole cooling system a good flush.

I have a thermal image camera so could give the rad a scan to make sure it's evenly cooling the water

 

[Red Oktober]

I'd move the number plate front the lower grill slots.....

It's worth giving the hole cooling system a good flush.

I have a thermal image camera so could give the rad a scan to make sure it's evenly cooling the water

hmmmm ...that could proove productive ...

i've already moved the reg plate

 

[Roger Fairclough]

A head gasket can blow in the following ways.

a) To the outside world. This will have no effect on water or oil, but will reduce power.

b) Into an oil passage. This will create extra pressure in the sump etc. This pressure will overcome sump seals etc creating oil leaks. Again, no effect on water.

c) Into a water passage. Large increase in water temp. Large increase in water pressure. Once it has started, it just gets worse and it will do so very quickly.

From the descriptions of events, I would change the stat. and flush the system. The red/brown silt is "normal", it's just rust. In theory it should not occur if the correct water/anti-freeze mix has always been used, but, in a car of that age, this is a bit pie in the sky. Hence my "normal" comment. If possible, remove the rad and flush separately. There may be a build up of sludge which may be freed by this method.

A hot day, 60-65 on the motorway for continuous periods, the air con on---all ingredients for pushing an aged motor past it's limits.

Roger

 

[Garry]

Hi

I had similar problem on a trip ,200 miles north and it boils .
Stop and repaced water , all was fine 30 miles boils again .This carried on for the whole of the return trip.
My thoughts were thermostate or head gasket , but had already replaced thermostat.Also I thought it may have been viscous fan unit .
The water temp had risen before when towing a large horse box ,reason for changing stat.

So next day when in worshop I took off top and bottom rad tanks , and there was the problem , large amounts of rust and crap blocking rad tubes .
therefore fitted new rad core .
Problem soloved.
This LJ 70 is 20 years old and i think this is the 3rd rad (75000 miles )

Garry

 

[Red Oktober]

Thanks Roger and Garry ...very helpful

 

[wobbly]

You could try a rad flush type product to help shift the sludge, does sound likely to be the problem.

The aircon rad sits in front of the car rad, means that the airflow was being pre-heated before it got there.

Only thing not mentioned is the water pump, that was the problem on mine that the previous keeper tried to avoid fixing by lots of pointless bodging.

Pete

 

[Red Oktober]

have now taken the rad out .... and the thermostat ....

this is whats left of the thermostat

on the bottom of the rad ... there are 2 smaller connections (next to the main water pipes) ...what's the red oil like stuff that's in there

i have put clamps on both the 2 pipes to stop any comming out just in case it's important.

 

[adrianr]

ATF and its your transmission cooler i would think.