Gus Driver

New Member
Hi All,

Recently acquired a p38 (on 98S plate, 4.8 HSE with GEMS). Loving it, but..... got an overheating issue I could do with help on!

Long story short, I think I need a new radiator, but would like to confirm before I start throwing cash in.

I've spend a bit of time on diagnosis using RAVE and online resources, and here's where I'm at:

1) Engine starts overheating after about 15-20 mins continuous use, even when gently cruising at about 50-60mph. Temp gauge rises steadily over about the next 10 mins until light comes on. On one occasion dumped about a litre of coolant through overflow pipe when I pulled to a stop.
2) Coolant levels checked and good. I removed radiator bleed pipe and filled until water flowed out top of radiator spigot.
3) System under pressure. Which is reassuring since documentation shows previous owners had new water pumps fitted in 2014 and then again in Jan this year!
4) Pipes in good condition throughout.
5) Radiator bleed pipe (from rad to expansion tank) clear.
6) I deduce (I hope correctly - please say!) that thermostat is ok. Water in pipe between bottom of rad and thermo housing is cool whilst engine temp warning up; and hot when engine overheating.
7) Radiator appears to be the original one. Some (not major) cluttering of old leaves and insects, etc present. Tellingly, though, the fins are crumbling on touch.

So what I think is that rad is just not acting as effective heat exchange so coolant flows through system just as it should but doesn't get cooled by the rad as it should.

Someone please let me know if I am making an obvious error (entirely possible - I have some but limited auto experience). And any practical advice at all very gratefully received.

Thanks in advance
 
Don't cook the V8 too much you risk losing a few liners and/or blowing a headgasket or two ;)

It could be a bad rad or $hitty Britpart waterpump.

or a airlock somewhere in the system.
 
I second what Henry said - in fact, I recommend you do not drive it much at all until you find the problem and fix it. The 4.0 and 4.6 are particularly prone to secondary problems caused by overheating (slipped cylinder liners and cracked blocks) which will require a very expensive full rebuild or a replacement engine.
 
Check the viscous fan is working as it should while you're about it. Newspaper test. I think yours is old enough for the air-con fans to kick in to help with overheating.
 
Check the viscous fan is working as it should while you're about it. Newspaper test. I think yours is old enough for the air-con fans to kick in to help with overheating.
+1 to the viscous. The aircon fans will only kick in, if at all, when it's too late to do much good.
I can give you a mod that will enable you to use the aircon fans as back up to the viscous fan.
 
I would seriously worry about this vehicle I guess it's been doing this since 2014. At 50 or 60 the viscous fan won't be doing much. A 98 will have blue antifreeze maybe the rad is clogged but four years overheating is not good for rv8 health.
If you own this common sense says change the rad. Descale. Refill with blue. If it still overheats suspect worst things.
 
Think your living in the past Keith, dont think they are printed these days.I may be wrong, its years since I bought a paper. ;)
How do you think they get the image on the paper if it's not printed? The method of printing has changed as has the ink which is now more toxic, but papers are still printed.
 
How do you think they get the image on the paper if it's not printed? The method of printing has changed as has the ink which is now more toxic, but papers are still printed.

Think he means the ink is more strongly bonded to the paper these days so you don't end up with black all over your fingers. Never bothered with papers: opinions and bull****.
 
Think he means the ink is more strongly bonded to the paper these days so you don't end up with black all over your fingers. Never bothered with papers: opinions and bull****.
Buy a paper and check it out, the ink still comes off and it's too toxic to use for wrapping your fish n chips.
 
Glad you realised what I meant,;):)


well I got the complete wrong end of the stick.. I thought you were implying that no-one buys the dead tree press anymore and uses online news instead.


if people still buy dead tree press.. how about a landyzone paper, with a page 3... with prink ink from collected oil leaks
 
Hi All,

Recently acquired a p38 (on 98S plate, 4.8 HSE with GEMS). Loving it, but..... got an overheating issue I could do with help on!

Long story short, I think I need a new radiator, but would like to confirm before I start throwing cash in.

I've spend a bit of time on diagnosis using RAVE and online resources, and here's where I'm at:

1) Engine starts overheating after about 15-20 mins continuous use, even when gently cruising at about 50-60mph. Temp gauge rises steadily over about the next 10 mins until light comes on. On one occasion dumped about a litre of coolant through overflow pipe when I pulled to a stop.
2) Coolant levels checked and good. I removed radiator bleed pipe and filled until water flowed out top of radiator spigot.
3) System under pressure. Which is reassuring since documentation shows previous owners had new water pumps fitted in 2014 and then again in Jan this year!
4) Pipes in good condition throughout.
5) Radiator bleed pipe (from rad to expansion tank) clear.
6) I deduce (I hope correctly - please say!) that thermostat is ok. Water in pipe between bottom of rad and thermo housing is cool whilst engine temp warning up; and hot when engine overheating.
7) Radiator appears to be the original one. Some (not major) cluttering of old leaves and insects, etc present. Tellingly, though, the fins are crumbling on touch.

So what I think is that rad is just not acting as effective heat exchange so coolant flows through system just as it should but doesn't get cooled by the rad as it should.

Someone please let me know if I am making an obvious error (entirely possible - I have some but limited auto experience). And any practical advice at all very gratefully received.

Thanks in advance
Twice in the past year I have seen evidence of what a bad effect an old radiator can do to a mostly normal good engine.
Our son has an ML 320 Merc, it was overheating and becoming unreliable to use as if you drove too far it overheated and left our daughter in law and grandkids stranded, he bought a new radiator on e bay, cheap, fitted it, no further problem.
Our daughter has a 2006 Ford Transit camper truck, it managed to keep its cool just tootling about town but would rapidly overheat on the freeway, we bought a new radiator on e bay, also surprisingly cheap, fitted the new rad to Transit, perfect result, even on sweltering summer days with a/c on full blast, engine maintains normal temp.
So in short, old radiators may look sort of ok, but the inside of cores get coated with scale build ups that impair in a major way heat transfer. Buy a new one it doesn't have to be oem or the most expensive.
 
Had this few years ago with couple of cars, sit ticking over all day no sign of over heat drive them hundred yards down the road and into the red, stick a new rad on it dont even waste your time trying to flush it out.
 
Had this few years ago with couple of cars, sit ticking over all day no sign of over heat drive them hundred yards down the road and into the red, stick a new rad on it dont even waste your time trying to flush it out.
Especially true of the stupid RAD design on the P38 diesel.
 

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