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I stand corrected.
P38A intermittent coolant pressure issue
- Thread starter kermit_rr
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Datatek
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To add to the above comment, on the diesel, metal water pumps produce a lot less flow than the original plastic item, making the cooling system marginal in ambient temperatures of 41C plus
RangeRoller dt
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My original (LR) unit lasted 138,000 miles. Hardest part was getting the bits of broken
Plastic out
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Done quite a few miles over the weekend and noticed once it's been up to temp for a while say 30-60 mins, there's a hint of a hiss from the expansion cap, ie its letting a small amount of pressure out.
When i open the cap when the engine is fully cold, there's still pressure in the system and the coolant level rises in the expansion tank.
Does this mean I've still got an air lock?
Even when sitting in traffic for ages yesterday, temp remained steady and didn't go over 94c. Not losing any coolant that i can see
When i open the cap when the engine is fully cold, there's still pressure in the system and the coolant level rises in the expansion tank.
Does this mean I've still got an air lock?
Even when sitting in traffic for ages yesterday, temp remained steady and didn't go over 94c. Not losing any coolant that i can see
Datatek
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Sounds like there may still be air in the system, but It might mean your pressure cap is not holding pressure, make sure it's screwed down good and tight, some of them are stiff to turn before they seal.
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Thanks, I'll try and give it more of a turn, I've been worried about over tightening it.
Also just thought about the LPG vapourisers, the gas isn't turned on at the track but if they are ruptured maybe that could cause a problem too.. but I'm not sure how the gas/coolant is separated
Might try removing them from the coolant circuit
Also just thought about the LPG vapourisers, the gas isn't turned on at the track but if they are ruptured maybe that could cause a problem too.. but I'm not sure how the gas/coolant is separated
Might try removing them from the coolant circuit
Datatek
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Failed vaporisers are not that unusual, certainly worth isolating them from the coolant circuit.
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That's my next job! And maybe a new jubilee clip on the top hose.. keep tightening, keeps leaking!! It's a new hose
Datatek
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If it lets water out, it can also let air in as the system cools.
spadgr
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If the cooling system is pressurising then it's not cooling enough or it's getting combustion gases in there. There could be heaps of causes. If it's had a stop leak in there then the radiator could be partially blocked (it could be partially blocked even if you haven't had a stop leak in there), the thermostat maybe faulty, sticking partially open, open enough to allow cooling under normal conditions but not opening enough to allow adequate cooling when needed. Corroded or broken water pump impeller, viscous coupling faulty.
I had an intermittent overheat on my 2.5 DSE and it was the viscous coupling, not saying of course that is your solution.
Try a new radiator cap, it wouldn't be the first time it's solved what seems to be a complex cooling problem. After reading all the posts, i reckon that's the first thing i would do.
good luck.
I had an intermittent overheat on my 2.5 DSE and it was the viscous coupling, not saying of course that is your solution.
Try a new radiator cap, it wouldn't be the first time it's solved what seems to be a complex cooling problem. After reading all the posts, i reckon that's the first thing i would do.
good luck.
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It's had stop leak, full of nasty copper flakes which caused plenty of issues. I think that's all flushed out now.
The water pump and viscous coupling are like new. The radiator seems to be completely clear - the coolant temp doesn't get above 94c even when sat in stationary traffic. The thermostat is working properly, I've replaced the cap and the expansion tank
There's definitely air somewhere in the system as the level in the expansion tank drops a long way as it gets hot. It doesn't show signs of over pressure until it's been fully hot for at least half an hour or maybe more.
Thanks
The water pump and viscous coupling are like new. The radiator seems to be completely clear - the coolant temp doesn't get above 94c even when sat in stationary traffic. The thermostat is working properly, I've replaced the cap and the expansion tank
There's definitely air somewhere in the system as the level in the expansion tank drops a long way as it gets hot. It doesn't show signs of over pressure until it's been fully hot for at least half an hour or maybe more.
Thanks
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Found another issue, the cheap expansion tank i bought, the screw thread goes soft when it gets hot!! Let's the cap pop off slightly. It's maintaining pressure but it can't be a good thing..
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Once hot it shouldn't repressurise.
biketeacherdave
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Replace the rad and all the hoses fill and bleed
Datatek
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When hot there should be about 14psi of pressure if the cap is sealing.
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That should read up to 14 psi. At normal engine temp at idle internal pressure should be not a lot more than 7 psi.
RangeRoller dt
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That water pump does spin fast
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Yep water pump spins faster than the engine RPM. That is why seized viscous fans are known to explode.
RangeRoller dt
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^^^ like my original. They take out rad and whatever they hit on the way out too
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Yep a seized viscous with the engine at 4000 RPM spins at around 7000 RPM. Viscous fans should never exceed 80% of engine RPM even when full engaged, there should always be slip.
