Thread: 3.9L V8 on heat - is this normal?

Gday, The first thing to do is sort out the temp guage, to assitain just what the temp is. Doest the car go hot moving or standing still? As has been said V8 dont like heat nad youll need to sort it ASAP. take the Radiator of and sent it to a Radiator repairers where they can take the side tanks off and put rods init to clean the crap out of it. A reverse flush wont do this. Replace the thermostat, with a new one and the cap. Ensure the fan is working right and ensure no air pockets are in the system. The Thermostat should open about 83 degrees.

If it was me:

I'd take out the thermostat and run it for a while and see what happens.

Cook some water in a pan over the stove, get it up to 85c with the thermostat in from cold. See if the thermostat is working...

Some time ago I had a few probs re this issue.

The thermostat was no good, the pipes to the heater and the heater itself, were no good, and one of the main hoses from the rad (the top one) collapsed under use, which was weird...

I replaced the main hoses, terminated (prior to) the heater, got a new t'stat and have been okay since...

Good luck.

Cheers, GQ

Originally Posted by muddydigger

Gday, The first thing to do is sort out the temp guage, to assitain just what the temp is. Doest the car go hot moving or standing still? As has been said V8 dont like heat nad youll need to sort it ASAP. take the Radiator of and sent it to a Radiator repairers where they can take the side tanks off and put rods init to clean the crap out of it. A reverse flush wont do this. Replace the thermostat, with a new one and the cap. Ensure the fan is working right and ensure no air pockets are in the system. The Thermostat should open about 83 degrees.

Hi,

I agree with you that I have to get the temperature gauge sorted first. The radiator has been taken out (with the sidetank off) last week. I'm assuming the point of taking the sidetank off was to clean it with a rod. The thermostat was also replaced at the same time. I'm certain the thermostat is opening up, as for no air pockets... I can guarantee there aren't any, but it's been done by a reputable mechanic who only does land rovers.

The only things I can think of is a blocked radiator (somehow), due to the high difference in radiator inlet and outlet temperatures, or that the pump isn't working very well.

However, given that I have driven it for some 10kms while it was "hot" (above 100 degrees at the radiator), and it hadn't cooked, I would say that it's either

a.) not fully blocked, or
b.) the water pump does work.

I'll attempt to sort out the temperature gauge, and then I'll take it to the mechanic for him to sort out. It really should have been picked up in the first place, especially since I pointed out that it was getting hot. Worst of all is that I was assured it was cooling just fine, and that everything had ben done.

Nehow, once he finds out what was wrong with it, I'll post on here.

Cheers

Bojan

Offender, sometimes and not often, sporadically, when I leave here, within about 5 mins, my temp gauge goes to about 3/4s, which is a bit of a worry...then it settles back to about 3/8s... I assume this is due to the t'stat not behaving....

...just a thought.

GQ

OK,

Update on the overheating problems... they're getting sorted now...

...replacing temperature gauge and sender unit with VDO ones. Mine is the older type 5/8 UNF thread, so I need an adapter as well.

The overheating seems to have been caused by an air lock in the radiator, that the mechanic unknowingly left after filling the radiator fluid. A series of unfortunate events led the mechanic to replace the 82 degre thermostat with an 88 degree thermostat, and more importantly, to add an additional hose that was supposed to help deliver coolant to the top of the engine. The V8 wasn't factory fitted, so the cooling system was "wired" differently from standard.

The mechanic didn't pick up on this, so when he refilled the coolant, he left a great big air lock in the radiator. What was worse, I noticed it "heating up" but he convinced me that it was just the gauge and assured me all was OK, (apparently a common fault with the temp gauges - Lucas gauge... need I say more!)

Nehow, for the next two hours or so, the engine was going in and out of the redline with me thinking that it was all fine I wasn't a happy chappy when I pulled over "just to make sure" and found the coolant boiling over out of the expansion tank!

As luck would have it, the head gasket seems intact, and the fact that the temperature gauge was working the entire time would mean that there was still water in the engine. So fingers crossed, a very lucky escape, as I've just been alerted to the nightmares that can result from a rover V8 overheating.

Several different mechanics I've spoken to seem to think that it'll most likely be OK. Fingers crossed they're right.

unless its synthetic I would change your oil now its fixed

so this means you can come on the next outing ???

Is this carbied? If so, you need that little hose to the manifold between the carbies so stop airlocks.

Personally, I'd replace the rad with a new one. On my SIIA with the 2.25 petrol, cooling was a big problem above about 35c, even after I'd flushed the rad. A new water pump and radiator fixed it.

Typical.

Offender, sometimes and not often, sporadically, when I leave here, within about 5 mins, my temp gauge goes to about 3/4s, which is a bit of a worry...then it settles back to about 3/8s... I assume this is due to the t'stat not behaving....

Sorry to be sanctimonious, but a thermostat is about $15. Head gaskets or slipped sleeve a little more. It WILL fail soon.

The overheating seems to have been caused by an air lock in the radiator, that the mechanic unknowingly left after filling the radiator fluid. A series of unfortunate events led the mechanic to replace the 82 degre thermostat with an 88 degree thermostat

3.9s are supposed to have an 88C thermostat. There is no harm in that, even if you have carbs on it. Do you?
If so you need the extra hose to the inlet manifold from the RH header tank. AFAIR no v8s come with 82c. they are just fitted by mechanics to give more headroom to overheat, which is pretty simplistic.
Regards Philip A