I am helping a friend with 97KX8 tensioner change. We have refilled the cooling system but can't seem to get the air out.
The heater is on high but no heat and the lower radiator hose is not very hot, acts like thermostat is not opening.
any suggestions? Temp runs right up to 220+ before shutdown.
RJ

 

Firstly be very careful, these engines do not like overheating.
Is the cooling fan running?

 

Remove Thermostat and see if that helps. if it does, you might have put the thermostat in backwards. If it does not, then you have blockage somewhere and you need to flush the system. These systems should not need burping to get the air out, as the reservoir is above everything else.

PS: when putting in a new thermostat, is a good idea to drill a couple 1/8" holes in the thermostat, that way you lower the risk of overheating.

 

Thanks guys. The fans are working and I think the thermostat is sticking. We did not remove it, just drained radiator to replace tensioners. I will replace thermostat with a spare.

 

When fitting the Thermostat, it's important to have the 'Giggle Pin' at the top as shown arrowed in the drawing:



This allows any air to bleed. The hole also allows some limited coolant flow if the thermostat sticks.

Graham

 

will look just like a bad thermostat. the impeller disintegrates and you get a no flow problem, cause overheating.

 

Yes, I'm familiar with water pump issue. I thought he said he replaced it already, but I'm going to have to check because the thermostat tested out on the stove and if anything opened wider and sooner than my spare.

 

It seems strange that you have this problem after just replacing the tensioner. You said the thermostat checked out OK, so it sure looks like the water pump is not working at all. I assume the car did not have this heat problem before you replaced the tensioner?

Bill N
03 XKR

 

It is strange, alright. He is only 15 min from me, and it's possible the condition existed previously. I just plugged my ultrgauge in when we were done so he could see what temp it was operating at.

 

He isn't here right now, but I think we should remove the water pump tomorrow morning. The fact that the lower radiator hose did not get hot and the heater didn't blow hot air on Hi sure makes the pump look suspicious. Of course the heater does have a valve and pump of it's own that could be at fault, and I doubt this car is driven in cold weather.
RJ

 

I started the car this morning and watched the Ultragauge during warmup. The temp increased smoothly to 197F, then held 195- 199 for a few minutes. It then began rapidly climbing and the cooling fan kicked in. When it went over 220 the second cooling fan started and I decided to shut it down. By the time I reached the key, maybe 2 sec. it was 230.
I waited 1 min, then restarted and the temp was 208, then fell to 197- 201 for a few minutes. I was thinking maybe it was settling down when it started the rapid climb to 220+, and I shut it down again.
This does not make sense. It should not rapidly overheat with the cooling system full and the thermostat open. Is the ECM putting out faulty data? Keep in mind this car was never run with a temp. gauge before yesterday. The Ultragauge does not show this kind of crazy behavior in my 97, it reads 195-203, in line with the Realgauge.
RJ______________
97 XK8 85K mi

 

Now you've eliminated Thermostat, Water Pump and Coolant level, the Temperature Sender has to be questionable when you're getting those kind of fluctuations.

Graham

 

This behavior is most likely an air lock. The very rapid temp rise is the giveaway. There is no bleeder on the system, just fill the coolant back up very slowly until it comes to the edge of the reservoir cap seal area. A bad waterpump could cause this also but it seems odd that it would start right after opening the system, that why I suspect the airlock, its the only thing related to the work you did. You might check the hidden overflow bottle (I think it's in the right fender) and see if it is full to the top.

 

Would it help starting it up with the filler cap off?
It certainly works when we get an airlock in a tractor and heck! there isn't that much difference.....

 

That should start some spirited discussion!
Graham

 

Can I borrow your sofa JIC ?

 

Interesting, I'm sure we all know that Aston Martin was begun as part of a tractor comany (David Brown....DB--6!) and Jaguar has some Aston Martin relatives.

 

And I think Standard Triumph's engines were the petrol Fergusons - but is running for a few minutes with the cap off likely to help or a Bad Idea?

 

With the coolant at the correct level (base of the filler cap neck) it will expand and spill over the top as soon as the engine starts to warm up. This excess normally goes straight into the Recovery Tank with the cap in place.

Didn't learn that today, but I shan't be repeating the experiment.

Graham

 

Thanks guys. I drove the tractor this morning and the temp spiked to 213 initially and then settled down to 190- 200. I left my Ultragauge in the car and the owner will keep track of the readings. If it acts screwy again the first choice will be a new temp sender.
AS to filling, I always leave the cap off after starting to be sure the level doesn't drop due to air in the system being expelled. Then when it cools down I check and top off. In this case it took about a pint (US measure).