Another overheating P38 diesel - sorry

Have looked at previous posts without success, so here goes.....

My '98 P38 diesel rapidly overheated last week having been running fine and centre of the gauge, (within seconds ), blowing the top tank on the rad apart. Have replaced rad now and following RAVE flushed, refilled and bled system, however it still overheats.

The thermostat is operating ok, the bleed pipe from rad is not blocked, there is no sign of water in the oil, nor oil in the water.

The heater is not blowing hot although the feed pipes appear hot.

There are no bubbles from the expansion tank or breather pipe whilst it is warming up, so I'm assuming head gasket is ok; however once hot/heading for overtemp there are lots of bubbles and it's forcing out lots of water, which I'm assuming is steam/vapour generated by the overheating.

Am I right in thinking that it is likely to be the water pump failing, causing overheating due to lack of flow, or does anyone have any other ideas? Could it still be the head gasket?

welcome. do you know anybody that can do sniff test for you local garage ?

that sounds like you're hinting it could be the head gasket?

no no its just a good place to start if you get all clear we can start going through it with you never start with doom and gloom overheating is some thing we all have at some time both petol and dosel

have you had a look at top on hether tank is it making a good seal? if not that could be your problem

The header cap is holding good, but I'd ordered a new one anyway after the rad blew, just in case it was too good, hence the pressure build up, also themostat. Have decided to go for replacing pump next, as cheapest option. Having replaced rad,pump,themostat and headercap, that really should only leave the head gasket, and if that needs doing then I'd have the pump done at the same time anyway.

may i be so bold to ask was your air con on when it overheated?

yes it would have been

I''d better add that it would have been working pretty hard too, as it was one of those 30+ days!!

kernowdragon said:

I''d better add that it would have been working pretty hard too, as it was one of those 30+ days!!

Click to expand...

Could be air con condensor fans not operating, try running with the air con switched off.

Don't want to be a prophet of doom, but worst case it could be a cracked head

Are the aircon fans also a supplimentary cooling source for the engine? I wondered that but could find no mention in RAVE so I thought they were purely for the aircon. Surely you couldn't rely on having the aircon on to add cooling effect, or are you saying the additional heat output from the aircon could be causing the rad not to cope? I've been running the engine without the aircon whilst working on the cooling problems anyway.

J the range - when you talk about using a sniffer are you talking about a standard exhaust gas analyser or something different?

a few of the lads on here have had overheating problems with air con on the fans at frount of rad are not comming on. just try taking plug off air con and run it. at least it will give you a clue to whats going on, now i hope you see why i said sniffer test first

It analyses the water and checks for combustion gases. You might also need a leak-down test.

yes the very same just to see if any leaks of gas j

Mad Hat Man - Off topic I know but... Great taste in beer!

wot - MHM old peculiar?

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Speckled hen's a good un

Sarah Hughes Rich Ruby Mild takes some beating.