The most obvious advice is not to knowingly drive it until the red light comes on. You may have already caused damage with getting it so hot it was belching coolant out the overflow. As the radiator is crumbling at your finger tips it is most likely at least partially clogged. Take the time to do a proper flush to clean out passages pipes and thermostat as well as your heater core.Get a new radiator ordered and do not drive it until you get this issue rectified.
P38 overheating issue
Hi All,Recently acquired a 1998 P38 HSE. 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 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 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. And any practical advice at all very gratefully received.Thanks in advance
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You do not have to "raise the expansion tank". We cross posted and I didn;t even see that.
The P38 should be on a level surface and bleeding is simple. Proper procedures are in RAVE under cooling system/drain and refill. No need to remove block drains. One bit that imperative is to ensure the overflow tube is clear. One helpful add on tip is to fill the radiator first using the upper radiator hose. It takes awhile to fill through the purge tank.
However all this is down the road. Flush your system using any off the shelf flush and follow their directions to clean out our your heater core, lines and block. This eliminates contamination of the new coolant from corrosion elsewhere in the system.
The P38 should be on a level surface and bleeding is simple. Proper procedures are in RAVE under cooling system/drain and refill. No need to remove block drains. One bit that imperative is to ensure the overflow tube is clear. One helpful add on tip is to fill the radiator first using the upper radiator hose. It takes awhile to fill through the purge tank.
However all this is down the road. Flush your system using any off the shelf flush and follow their directions to clean out our your heater core, lines and block. This eliminates contamination of the new coolant from corrosion elsewhere in the system.
I would flush the system just to clean the block and lines of any crud, then fit a new radiator and, like Toad says, make sure the overflow line is clear.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.
I had the small hard lines breaking up on my car when it overheated (thermostat housing cracked) so I replaced them all with flexible lines.
Just wanted to say "thanks" to those that replied (whether by above or private message) - you gave me the confidence to go for it on replacing the radiator - and saved me panicking when i experienced the dreaded nut and bolt corrosion/fusing at the bottom bracket!
New rad plus flush and refill have pretty much cured the issue. One minor symptom remains, on which I'd much welcome further guidance.
The handbook symbol comes on the air con when engine up to temperature (or shortly thereafter). The temp gauge then creeps slowly up to virtually the top of the normal range on the gauge (no light indicating overheating). If I turn a/c off and heater temp right up (to HI or near HI) it brings engine temperature down to mid gauge within 30-60 secs. So it's a relatively minor gripe that I can live with to avoid engine seizure. That said, it'd be nice to get a proper fix rather than rely on the cabin heater to be augmenting the radiator's job!
In doing the work on rad replacement I noticed a couple of things that are almost certainly relevant (?)
1. A/c condenser is pretty clearly shot - must be the original - fins falling out all over the place !
2. The auxiliary fans (in front of the a/c condenser) don't kick in at any point. I'm guessing they should when the engine temp gets high and there is an increased demand/load from a/c to cool.
I'm deducing that I need a new condenser complete with fans. Plus a regas.
Just want to check that my logic above sounds right - and that this is a fix I can do myself (comparable to radiator replacement)? Looks it from research I have done, but I don't want to get overconfident or underestimate the niggly bits ! And/or if there is a well known issue e.g. electrical that might be stopping the fans kick in (NB I've checked fuses, all fine) then someone may be able to give me a cheap and easy save here?!
Thanks in advance.
New rad plus flush and refill have pretty much cured the issue. One minor symptom remains, on which I'd much welcome further guidance.
The handbook symbol comes on the air con when engine up to temperature (or shortly thereafter). The temp gauge then creeps slowly up to virtually the top of the normal range on the gauge (no light indicating overheating). If I turn a/c off and heater temp right up (to HI or near HI) it brings engine temperature down to mid gauge within 30-60 secs. So it's a relatively minor gripe that I can live with to avoid engine seizure. That said, it'd be nice to get a proper fix rather than rely on the cabin heater to be augmenting the radiator's job!
In doing the work on rad replacement I noticed a couple of things that are almost certainly relevant (?)
1. A/c condenser is pretty clearly shot - must be the original - fins falling out all over the place !
2. The auxiliary fans (in front of the a/c condenser) don't kick in at any point. I'm guessing they should when the engine temp gets high and there is an increased demand/load from a/c to cool.
I'm deducing that I need a new condenser complete with fans. Plus a regas.
Just want to check that my logic above sounds right - and that this is a fix I can do myself (comparable to radiator replacement)? Looks it from research I have done, but I don't want to get overconfident or underestimate the niggly bits ! And/or if there is a well known issue e.g. electrical that might be stopping the fans kick in (NB I've checked fuses, all fine) then someone may be able to give me a cheap and easy save here?!
Thanks in advance.
Gus, You and I are doing similar jobs at the mo. I have a new transmission cooler to fit, and a new condenser. Neither sound too traumatic tbh. My A/C feed pipes came off the condenser without issue. I have a new inlet pipe for the gear cooler as it is most likely welded on at the condenser end, that's still to do. With your fans I suggest you bridge the relays and you may find that the fans do in fact work (but since your a/c isn't working the relays themselves don't activate, as you say). I did with mine and proved that they work (even though they looked dead)... then I'll regas, and no doubt find some other issue to solve. Rob
Sounds like the overheating did do some damage, you can control it to a degree through the cabin heater, but eventually you will have to do the head gaskets, and heater Orings to be on the safe side, keep an eye on the r/h floor for wetness.
Hi. Original poster picking up on this again. I had the a/c vacuum tested and regassed (fair play to In 'n' Out who did it for £49 inc 1300g of refrigerant). Drove 500mile round trip in really hot weather and needed to manage engine overheating through regularly turning cabin heater to full.
The condenser fans aren't kicking in. My reckoning is that if they did, then I wouldn't get overheating (or, at least, I'd get less).
Sometimes on the HVAC cabin controls the handbook sign shows, then disappears, then shows again. I'm thinking that's consistent with pressure switches "calling off"/demanding the condenser fans start-up; with fault then showing because the fans don't start up as the pressure switches demand (and fault going off again once pressure switch removes the demand)?
I've checked fuses 34, 42 and 43 - fine.
After looking at RAVE and internet I've had an attempt at bridging relays 6 and 7 to see if the fans will work and duff relay(s) might be the cause - I may be doing wrong (would welcome instructions/guidance), but the fans still don't work.
Any guidance/help welcomed !
Still in love with the car despite myself.....
The condenser fans aren't kicking in. My reckoning is that if they did, then I wouldn't get overheating (or, at least, I'd get less).
Sometimes on the HVAC cabin controls the handbook sign shows, then disappears, then shows again. I'm thinking that's consistent with pressure switches "calling off"/demanding the condenser fans start-up; with fault then showing because the fans don't start up as the pressure switches demand (and fault going off again once pressure switch removes the demand)?
I've checked fuses 34, 42 and 43 - fine.
After looking at RAVE and internet I've had an attempt at bridging relays 6 and 7 to see if the fans will work and duff relay(s) might be the cause - I may be doing wrong (would welcome instructions/guidance), but the fans still don't work.
Any guidance/help welcomed !
Still in love with the car despite myself.....
if its still running hot after the rad replacement I would be looking at water pump ?
The hevac fans are nothing to do with the other rad, nor would they make much difference, they don’t come on very often anyway.
looks like it’s head gasket time, don’t go down the route of sticking one of the so called sealers in,
it will block everything up, nightmare stuff !
looks like it’s head gasket time, don’t go down the route of sticking one of the so called sealers in,
it will block everything up, nightmare stuff !
RL6 & RL7 are for the heater fans. The condenser fans are driven via RL13 & RL14, and depend on the A/C Dual Pressure Switch.Hi. Original poster picking up on this again. I had the a/c vacuum tested and regassed (fair play to In 'n' Out who did it for £49 inc 1300g of refrigerant). Drove 500mile round trip in really hot weather and needed to manage engine overheating through regularly turning cabin heater to full.
The condenser fans aren't kicking in. My reckoning is that if they did, then I wouldn't get overheating (or, at least, I'd get less).
Sometimes on the HVAC cabin controls the handbook sign shows, then disappears, then shows again. I'm thinking that's consistent with pressure switches "calling off"/demanding the condenser fans start-up; with fault then showing because the fans don't start up as the pressure switches demand (and fault going off again once pressure switch removes the demand)?
I've checked fuses 34, 42 and 43 - fine.
After looking at RAVE and internet I've had an attempt at bridging relays 6 and 7 to see if the fans will work and duff relay(s) might be the cause - I may be doing wrong (would welcome instructions/guidance), but the fans still don't work.
Any guidance/help welcomed !
Still in love with the car despite myself.....
You should check the Thermostat (take it out and put in a kettle to see if it opens correctly), and get the cooling system pressure tested for leaks. Also check the spark plugs for "steam cleaning" which can indicate head gasket issues.
Lastly, where in UK are you ? Might be somebody nearby with experience on this.
Shame we have to deduce where the OP is from by him putting a pound figure in an amount of money............
Martin
Martin
My 2 cents is to just replace the water pump, rad and tstat. Cooling system on a P38 is fairly easy to work on. I replaced all those three things for less than $400.
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