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V8 Using Coolant

Hi All,

After a bit of advice before the my 130 goes on a long trek. It's a V8 running an LPG conversion.

I've had a couple of dodgy thermostats that failed to open until the engine was very hot - needle well into the red. The latest thermostat from a different supplier (same opening temp) has cured that and now it's not going into the red before the thermostat opens. I've also had a new coolant temperature sensor (recently) and water pump (oem about a year ago) - the gauge has not been replaced but it appears to be working

- i.e thermostat opens and it drops back.

I had to replace the water pump gasket on the weekend as it had blown out at the bottom and was dripping coolant. After re-filling the system the gauge gets to the top of the white, thermostat opens, gauge drops to midway and all seems fine - plenty of power. I did a short journey, topped up the coolant and all was fine. Checking after doing about 100 miles the coolant level was about an inch down in the radiator so I topped it up, after running another 100 miles it had again used some coolant. No signs of emulsified oil - and the tiny bit of oil that leaks from the sump looks fine.

Am I worrying unduly that the thermostat opens only a little before it goes into the red or could it be something more sinister. Any ideas thoughts or things to try would be most appreciated.

Cheers.

Andrew

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1990 Ex Southern Electric 127
Reply to
Andrew Rawlins
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Take out the plugs, check for one that looks washed clean, if you find one.....

Reply to
Nige

How has the LPG system been plumbed into the coolant pipework and what inlet manifold/carb are you running? An edelbrock manifold with a webber 500 carb will give this initial temp rise before the stat opens due to it having no bypass pipe at the stat. Badger.

Reply to
Badger

I'll give that a try - ta!

Reply to
Andrew Rawlins

It was plumbed in by the heater matrix - which I have since had to replace - all of the coolant has been drained and replenished several times since then though.

Bog standard twin SU. On the way to work (2 miles) it started to creap towards the red and the thermostat opened as I pulled up - the pressure cap then vented some coolant onto the floor.

Andrew

Reply to
Andrew Rawlins

Two things spring to mind here:-

1, If there is a fault with a leaky diaphragm in the gas vapouriser then the gas can get into the cooling system and overpressure it, blowing out a little coolant at a time until the coolant level is low enough to cause thermostat issues, as the stat has to be totally immersed to work. A rare failure mode, but I have seen it once in 6 years! 2, Normally, the coolant is circulated past the back of the stat to make it react to coolant temp before the temp goes too high, as you are experiencing. This circulation is via the short hose coming off the front of the inlet manifold and feeding into the rear of the water pump. If the front timing cover has been replaced at some point with one from a rangerover efi, then the coolant hose connection at the back of the water pump may be plugged with a freeze (core) plug as the rangie version has a different coolant hose layout. If this has happened, then the coolant cannot circulate past the stat during the warm-up phase, the stat only opening due to conducted heat within the stationary coolant in the front half of the inlet manifold. I've never seen a blockage in the actual bypass hose itself, but it isn't unheard of for hoses to de-laminate and internally block.

If it were mine, I'd monitor the temp of the bypass hose from a cold-start and see if the hose actually warms up properly (gets HOT!)before the stat opens. If it does, you've a stat issue, if it stays cold, then pull the hose and check the hose and connection stubs on the timing cover. Oh, and have a good sniff for gas in the coolant header tank as well, just to be safe. Badger.

Reply to
Badger

Thanks for the replies Nige and Badger, it turns out the head gasket was slightly failing - the garage was too busy to do it so they let me do it myself and use them for some space and advice as I was going along (first real major surgery I've done on the engine itself).

After replacing the gaskets a trip from Aberystwyth -> Stornoway via Islay and Fort William went faultlessly - one happy 21yr old 130 :)

Cheers,

Andrew

Reply to
Andrew Rawlins

Stornoway, eh? That's a long haul for you in a 130! Take it you got the Uig > Tarbert ferry, not the Ullapool > Stornoway one, and I assume you found the LPG pump at Engebret's filling station in Stornoway ok? Badger.

Reply to
Badger

That ferry on the way up from Islay - great little drive that.

Came back that way from the Hebredian Celtic Festival - they put a special 06:15 ferry on for us - then it was Ullapool to Aberystwyth ~12 hours with only me driving - it was surprisingly ok. The ~2 hourly LPG stops really helped with the journey though. Late afternoon lunch in Tebay was welcome!

Ineed, starting to be able to spot them :) Reasonably priced too!

Cheers,

Andrew

Reply to
Andrew Rawlins

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