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Hello everyone I am a complete newbie to Range Rovers but have always wanted one and have just bought an LPG 1991 3.9 EFI Vogue Se Auto, and I love it :).

The only problem is that when the engine is warm and up to temperature, pressure builds up in the header tank and water is expelled quite violently. (as soon as i notice I always stop and switch off). Shes done this twice this week and i've given her a complete service, checked all the hoses, and there is no evidence of overheating or a knackered headgsket, i've even done the die test and it stayed blue. Otherwise she drives great, smooth, no smoke from cold and firing on all cylinders. There is also absolutely no evidence of leaks from anywhere else, including the Heater Matrix.

I ran her stationary and on idle for about half an hour earlier (very hot day) with the header tank cap off (new), there was no bubbling or steam, however the coolant gradually rose to the top and began to gently overflow, when i switched off the ignition it overflowed much more quickly. (This doesn't seem normal to me from previous experience, but I have no experience with Rangies and big V8 s lol) . She was standing in someone's garage for about 6 months before I bought her, so I suspect a blockage somewhere in the system or an air lock.

Any suggestions or advice would be greatly appreciated, Warmest Regards
ROB
 

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Re: HELP! Coolant Pressure-Overflow through header tank-

As far as I know there are only threee reasons for this symptom.

1. Blown head gasket. Pressure from compression geting into the water jacket. If you have done the chemical test that looks for hydrocarbons (blue dye?) and it is clear then this is almost certainly not the problem. But not definately.

2. Weak mixture. Bad inlet manifold gasket causing weakening ofmixture which burns far too hot and causes the overheating. Possible.

3. Blocked radiator core or stuck thermostat. Very possible.
 

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Thankyou very much for your help :) I had a good look this afternoon, the Rad seems fine and flowing freely, and I really dont think its the head, as it has no symptoms and was done quite recently, so ive ordered a new thermostat, only a fiver :)fingers crossed :)

Warmest Regards
Rob
 

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just to save you might change the filler cap - cheap and what you descript for me the reason for your troubles...
 

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Hey thanks for the replys, yer I replaced the filler cap with a new one, as that was my first suspicion aswell, but it didn't solve the problem, and yes im only filling it to the top of the marker.( I learnt that lesson before in a previous car lol :) I also did an air bleed and quite alot of air came out, so that could have been the issue, with such a big system. Anyways i'll do the thermostat anyway as it was so cheap, can't hurt. :) he says he he.

I'll let you know how it goes, nice and hot weather at the moment do should be a good test.

Warmest Regards and thankyou.
 

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Hi, I'm in Texas with mine and am experiencing a very similar issue. I checked everything, even removed the thermostat as so many of us do here. I have been reading alot of these posts and have noticed that my intake gasket is leaking. I'll order the parts this week and hopeful have it repaired by next. I'll let you know how it turns out.
 

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I agree with TehPriest. The most likely cause of constant coolant loss through the header tank is a blown head gasket. A coolant gas analysis will prove the point beyond doubt. The poor man's test is to remove the coolant cap when the engine is cold and then to start the engine. A head gasket failure that admits exhaust gasses into the coolant will put a steady stream of bubbles into the header tank. Left to get worse on its own, the coolant will eventually enter the combustion chamber and create sweet smelling steam, vast rolling clouds of it, even on a hot day. The thirst for coolant will grow undeniable.

Now, you have to wonder what failed. It's probable that the head gasket failed. That's common enough on any engine with moderate mileage on it (you didn't say how many miles, but RRC's this age have miles). It's also possible that a cylinder liner has slipped, and that is an unpleasant prospect. Slipping a liner is actually a fairly common failure on Buick/Rover aluminum V-8's. The only way to know is to take the heads off and look.

Scott
 

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You could put a pressure gauge on it, as a good shop will know how much pressure the system will build up normally and if its over that then its head gasket.

Put my dollar on the head gasket. Done a few :(

Also as far as the radiator goes, I have mine rodded fairly often, I have found the flow through the radiator can stay pretty good and not appear blocked, but its really blocked upto 75% in the middle just there is still enough of a path not to cause back pressure.
 

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The radiator cap always vents at a fixed pressure. I think mine vents at 14 psi, if I remember the printing on the box from months ago. A pressure gauge on the coolant system would only indicate that you approach the cap's release pressure. It might detect a bad cap that vents at a lower pressure, or the extremely unlikely event of a cap that doesn't vent at all, but it probably wouldn't be worth the effort.

If you have an exhaust gas analyzer around (like at your mechanic's shop, or at a state emission testing station) then you can have it sniff the vapors rising from your header tank. If it detects HC (unburned hydrocarbons) rising from your coolant, then you almost certainly have a head gasket failure. If not, then you have peace of mind.

Scott
 

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Hi all,
I appear to be having the same problem. I am noticing a very slight coolant loss overtime, not enough that it raised an alarm until some mountain driving. When working hard to maintain speed on the Colorado mountain highways, my dash coolant light lit up. I pulled over and noticed some coolant in the engine bay and it looked like it was coming from the expansion tank cap. A lot of pressure appeared to be built up, I am going to change the cap as a first check, but I have a feeling this is going to be my head gasket going. If I end up changing the head gasket, is there anything else I should do at the same time?

Thanks for the help; I am a newby to Rovers, but not old 4x4's.
 

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Discussion Starter #12
Hello everyone, thankyou for all your replys :), well I've changed the thermostat, checked all the hoses, replaced the inlet manifold gasket, flushed and replaced the coolant and done every possible head gasket test and it is definately not that, and it was changed recently anyway. Unfortunately the exact same overflow problem still occurs, I'm hoping to get hold of a pressure tester that fits soon....but its looking like a blocked rad at the moment, i'm gunna replace the header cap again anyway just in case, as they are so cheap.

Does anyone have any other thoughts? Thankyou So Much :)
 

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HI Guys

Please keep this post updated, I have the same problem and would love to know what the end result is.
Hope its not the CHG.
thanks
markus
'90 RRC
 

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Discussion Starter #15
Hi, thankyou for all your help, I didn't wait to confirm it, but it looks like a cracked head, as I found a recent receipt for a reconned rad in the history lol, I'm afraid i've sold her to a farmer friend for 400 quid to use on his fields lol, a loss of 350 quid, but hey sometimes you've just gotta cut your losses and run. NVM,

Thankyou once again.
 

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Hi ALL, im having the same problem, coolant through expansion tank overflow, new cap fitted . the weird thing is if it was a cylinder head gasket/cracked head , one would expect it to boil over every time the car is in use. mine can do a 60 mile trip, one day with nothing been lost through overflow, and other times she boils at the header tank within 10 mins. I believe another pointer to HG Failure is a rock hard rad top hose ? mine stays soft and pliable, can i assume my HG is ok ? any pointers will be appreciated
Regards Andy
 
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