Diesel cooling system problems

Gazza36 · Jun 28, 2015

Dear all, apologies if this has already been covered elsewhere but it seems quite specific, so recently the radiator hoses would remain hard even after a whole day standing and were starting to work their way off the radiator. Upon undoing the expansion tank cap the pressure would release. So I replaced the cap with a spare one I had and that seemed to solve the problem.

However, now the hoses are coming off again, but not staying hard and coolant is leaking from the cap. The head was replaced about eighteen months ago so I will be slightly upset if the head gasket has gone already, it has to go in to the garage anyway because some of the injectors are leaking, any help greatly appreciated.

wammers · Jun 28, 2015

Needs a static and dynamic pressure test. Static should hold 15 PSI without falling. Dynamic pressure test should run at 5 to 7 PSI warm at idle. Also get the cap tested.

Gazza36 · Jun 30, 2015

Going in Thursday, I'm guessing the static test is with the engine off and if the reading is low it indicates there is a leak somewhere, i.e. the head gasket, and the dynamic is running and if that is high it is because the gases are getting in, cheers.

wammers · Jun 30, 2015

Gazza36 said:
Going in Thursday, I'm guessing the static test is with the engine off and if the reading is low it indicates there is a leak somewhere, i.e. the head gasket, and the dynamic is running and if that is high it is because the gases are getting in, cheers.

Yes apply tool engine off and pressurise to 15 psi. Pressure should hold. Apply tool and start engine pressure should be 5 to 7 psi at idle when engine up to temp. Any fast rise in pressure above that at this stage would mean gas is entering system.

Datatek · Jul 1, 2015

Gazza36 said:
Going in Thursday, I'm guessing the static test is with the engine off and if the reading is low it indicates there is a leak somewhere, i.e. the head gasket, and the dynamic is running and if that is high it is because the gases are getting in, cheers.

Sadly, a cracked head is more likely then HGF

Gazza36 · Jul 23, 2015

Ok so eventually i just bought a pressure tester, it holds 15psi no problem at all but when running the gauge shows nothing, am I doing something wrong? Cheers.

Dippypud · Jul 23, 2015

Gazza36 said:
Ok so eventually i just bought a pressure tester, it holds 15psi no problem at all but when running the gauge shows nothing, am I doing something wrong? Cheers.

Have you bled it properly ?
P38s are a pain to bleed well ....

Gazza36 · Jul 23, 2015

Dippypud said:
Have you bled it properly ?
P38s are a pain to bleed well ....

I am going to flush the system and start again.

Dippypud · Jul 23, 2015

Gazza36 said:
I am going to flush the system and start again.

The drain plug is at the bottom of the radiator AND there is a drain screw on the cylinder head (tricky to find, its located underneath),
once drained, put screw and drain plug back in, fill up at header tank until you can get no more in, start engine, keep topping up until it will accept no more, top hose will become hot after 10 mins or so. re check over next few days.
On the first refill you can squeeze all the hoses to get air out.
It takes a minute or so of the engine on until the level goes back down again then you need to make sure you have enough coolant mixture made up to top up with...
50/50 mix of GOOD anti freeze....follow the instructions on RAVE.

Gazza36 · Jul 26, 2015

ok so i have refilled the system but still get water coming out of the overflow pipe?

wammers · Jul 26, 2015

Gazza36 said:
ok so i have refilled the system but still get water coming out of the overflow pipe?

Have you checked the seals on the cap?

Gazza36 · Jul 26, 2015

It is a brand new cap, they seem to be ok, could it be something wrong with the expansion tank?

Grrrrrr · Jul 26, 2015

When I refill mine I leave the engine running and squeeze each pipe like I'm inflating a blood pressure monitor. Then top up and continue. Sometimes it goes straight in and others it is a complete PITA.

Gazza36 · Jul 26, 2015

ok so i had another look, pressurised to 15psi with the engine off and warm, I can't test it running because for some reason the tester doesn't seem to be able to work like that, this time I noticed that the pressure did drop really slowly and I would get a drop of water come out of the overflow pipe, when driving it will lose coolant from this pipe.

Gazza36 · Aug 1, 2015

Ok so managed to read some pressure while running after a decent time, it had reached about 3 psi when i stopped, should i leave it running longer to reach 5 to 7 psi and should i get it sniffed? Cheers.

wammers · Aug 1, 2015

Gazza36 said:
Ok so managed to read some pressure while running after a decent time, it had reached about 3 psi when i stopped, should i leave it running longer to reach 5 to 7 psi and should i get it sniffed? Cheers.

If it is only getting to 3 psi after a short run it will be fine. If you had a combustion gas leak it would shoot up a lot quicker and to a much higher pressure than that.

Gazza36 · Aug 16, 2015

ok so the radiator may be leaking from the join along the bottom, could this cause the dribble from the overflow? cheers

tarphenry · Aug 16, 2015

I dont see how a leak from the bottom will cause the overflow at the top to dribble. have you checked the viscous fan, if thats not working ,its not forcing air through the radiator at low road speeds

Gazza36 · Aug 17, 2015

Just clutching at straws, the fan isn't that old but then I guess that doesn't mean anything with these as the radiator isn't either, the place where I got it said he has a customer that's been through three in a not considerable amount of time. The new tank is fitted so I shall see if that makes any difference.

Grrrrrr · Aug 17, 2015

Is the thermostat good?

Diesel cooling system problems

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