Overheat - Am I missing something

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timh1970

New Member
Posts
59
As time passes I am building up quite a collection of spared bits that there's nothing wrong with.

Viscous fan
Radiator
and
Thermostat

This time.

I have just bought an aftermarket britpart radiator and fit it over the weekend because I had overheat issues when towing, even though I had already changed the viscous fan and the thermostat.

I drove the car around 100 miles today and it sat around 99.1 and went up to 105 on steep hills (at which I bottled it and put the heater on with the windows down to keep it cool). Now I know that everybody says that these things run hot, but 99 - 100 under normal load still seems a little hot to me.

When I stopped I got out and had a feel of the bottom of the radiator after 100 miles and didn't burn my fingers. Now to me these radiators defy the laws of thermodynamics and I have also heard rumors that Britapart radiators do not have baffles in them so I was wondering if anybody else knew anything about them, and more to the point: How on earth is the hot water supposed to get to the bottom of the radiator?:confused:
 
I take it this is a diesel. Radiator MUST have a baffle in the header tank if not hot coolant just flows across the top of the rad. The baffle forces coolant down one side and up the other. Britpart strikes again. The diesel thermostat opens at 80 degrees petrols run around 88 degrees.
 
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Yes it's a diesel, I haven't checked to see if it has baffles in it or not but in my opinion it is nowhere near hot enough at the bottom.

If the stat opens at 80 I would not expect it to get much above 95 even at max load. To be honest the only other thing that it could be is the head gasket but I don't think that the temperature would drop as fast as it does (a matter of seconds) when the load is reduced if it was the head gasket.

I have just found another thread on here that shows a marble test so I will take the rad out tomorrow and test it
 
And name and shame both the make and where you got it from if it doesn't have a baffle because they shouldn't be allowed to trade. The amount of damage you could do because some idiot sells you a fake Chinese rad - or worse still a badly designed rad from a named brand.

Mine was an Allmakes one that didn't have a baffle. I never did get an explanation of their investigation, but I did get a full refund.

Of course you could just have an airlock :)

Nik
 
So today I took the radiator out (Again) and it does have a baffle inside (still seems a little cool at the bottom for me but, hey ho!)

Anyways I swapped the thermostat for a genuine one while I was at it; don't know what called me to do it, but it did make a difference. On a serious hill at "Cough" MPH it will still rise to 102.5 but that is well down on what it was, even with the heater on full before.

Most of the time on motorways I am getting 99.8 which can drop to 96.4 when it is not working too hard on an "A" road. This is with a properly hot engine on a fairly warm day. I personally think that this is still a little high but the gauge remains pretty much in the centre so I am wondering if this is within normal operational parameters (Particularly it getting to 102.5).
 
Not exactly sure what is correct, but mine seems to run at about 95C most of the time. Higher temperatures are more efficient up to a point and help with emmisions. Hope you put the stat in with the bleed hole at the top.
 
Yes, I'm running nipple up :D . I gave it as much stick as I dare today and the gauge did not move from 12 o'clock once it had warmed up. After about 70 miles I got back and opened immediately opened the cap on the expansion bottle which gave a slight gentle hiss as I would expect on any car (It certainly wasn't boiling) so happy days (touch wood).

For anybody who is having issues, the aftermarket thermostat that was causing the problem was a German made one that didn't have a nipple. These thermostats are dual purpose in that they open flow to the radiator in the normal way and close off flow to the engine recirculation duct using the disk at the bottom to plug the hole in the centre of the thermostat housing; Both have to function correctly or the engine will overheat. My recommendation for thermostats is buy genuine every time (and with JLR, I'd get 'em while they last!)
 
timh1970 said:
Yes, I'm running nipple up :D . I gave it as much stick as I dare today and the gauge did not move from 12 o'clock once it had warmed up. After about 70 miles I got back and opened immediately opened the cap on the expansion bottle which gave a slight gentle hiss as I would expect on any car (It certainly wasn't boiling) so happy days (touch wood).

For anybody who is having issues, the aftermarket thermostat that was causing the problem was a German made one that didn't have a nipple. These thermostats are dual purpose in that they open flow to the radiator in the normal way and close off flow to the engine recirculation duct using the disk at the bottom to plug the hole in the centre of the thermostat housing; Both have to function correctly or the engine will overheat. My recommendation for thermostats is buy genuine every time (and with JLR, I'd get 'em while they last!)
Click to expand...

Problem with non vented stats is that air is trapped on refill. Providing the stat is working correctly drilling a 2.5 mm hole in it and placing it uppermost would be a stop gap repair.
 
Today I took my rangie over snake pass and as I got up to the top it overheated (106). I pulled over onto a layby and opened the expansion bottle to a gentle and fairly brief hiss like you would from any normal car. The viscous fan was going for it and all seemed well. By the time I had got back to look at the gauge (around 30s or so) it had gone back down.

It only does this now on very heavy load; it will sit in traffic all day and is now perfectly happy on motorways although the temperature goes up a bit under load it is not huge.

One thing I have notices is that the oil cooler is missing the bottom row of fins which got me to wondering if this could be an oil cooling issue rather than a coolant one.
 
timh1970 said:
Today I took my rangie over snake pass and as I got up to the top it overheated (106). I pulled over onto a layby and opened the expansion bottle to a gentle and fairly brief hiss like you would from any normal car. The viscous fan was going for it and all seemed well. By the time I had got back to look at the gauge (around 30s or so) it had gone back down.

It only does this now on very heavy load; it will sit in traffic all day and is now perfectly happy on motorways although the temperature goes up a bit under load it is not huge.

One thing I have notices is that the oil cooler is missing the bottom row of fins which got me to wondering if this could be an oil cooling issue rather than a coolant one.
Click to expand...

If all you got was a brief hiss when you undid the expansion cap, perhaps the cap is not sealing properly, I would expect more than a brief hiss and some scalding water if it was that hot.
 
Datatek said:
If all you got was a brief hiss when you undid the expansion cap, perhaps the cap is not sealing properly, I would expect more than a brief hiss and some scalding water if it was that hot.
Click to expand...

So would I, but this is a Range Rover P38 so I am not taking anything for granted ;).

It is definitely not boiling up. That's the odd thing. If I were to ignore the gauge then it is running perfectly. I would have suspected a faulty sensor except that it only goes up when the vehicle is under load.
 
timh1970 said:
So would I, but this is a Range Rover P38 so I am not taking anything for granted ;).

It is definitely not boiling up. That's the odd thing. If I were to ignore the gauge then it is running perfectly. I would have suspected a faulty sensor except that it only goes up when the vehicle is under load.
Click to expand...
Viscous fan is the usual culprit, or silted RAD, water pump & stat. Could still be the sensor.
 
Datatek said:
Expansion tank cap, leaks from hoses etc.
Click to expand...

i have checked just about everything now. I have had it on test for a week and I can now tell you where I am on my way to work and back by looking at the temperature gauge. It is not overheating in the real sense of the word unless I get on a major hill, but next year my better half is going to be driving it towing a caravan and my life will be about as worthless as a triplet of dead rats in a tampon factory if it breaks down (I'm already in enough trouble for buying it in the first place; so much so that I am now mending it in secret).

I have a sneaking suspicion that the head gasket is on its way out. Not enough for a sniffer to detect but just enough to cause problems under heavy load, either that or the head bolts are loose.

I need to do the timing chain anyway so might as well give the engine an overhaul.
 
timh1970 said:
i have checked just about everything now. I have had it on test for a week and I can now tell you where I am on my way to work and back by looking at the temperature gauge. It is not overheating in the real sense of the word unless I get on a major hill, but next year my better half is going to be driving it towing a caravan and my life will be about as worthless as a triplet of dead rats in a tampon factory if it breaks down (I'm already in enough trouble for buying it in the first place; so much so that I am now mending it in secret).

I have a sneaking suspicion that the head gasket is on its way out. Not enough for a sniffer to detect but just enough to cause problems under heavy load, either that or the head bolts are loose.

I need to do the timing chain anyway so might as well give the engine an overhaul.
Click to expand...
Sadly, it is the classic symptoms of a cracked head. HGF is less common.
 
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