Help with my V8 Discovery

Hi I have a 1998 Landrover Discovery V8i (LPG) converted

Over the last couple of weeks I have had a problem with the coolant.
The Vehicle tends to pressurize and forces coolant out of the cap on the header tank. I have tried to solve my problems by having my car checked at a garage to see if the head gasket`s have gone, but both garages have told me that they have not gone.
I have put a new cap on the header tank also just in case.
I am still using my car and over the Christmas weekend I took it to Glasgow for the weekend. I Live in Ashton In Makerfield near Wigan, a trip of around 500 miles in total and no problems apart from the heater stopped working. It would only blow out cold air. I got us home to Ashton and bought a new thermostat. I put it in and now the heating is a bit of a hit and miss sometimes working other times not.
Any help or input would be much appreciated many thanks.

Sounds like an airlock in the cooling system if your 100% sure it's not head gasket

shut the gas down, try running on petrol as gas vaporiser can cause problems if faulty.

The liquid hydro carbon tests are crap. the best way is
gas analyser probe under bonnet and start engine(background hc)
hold over coolant header tank-jumps =hc and hgf /liner etc.

well its being pressureised and getting air in it to lose ya heater

so i'd put my money on a HG fail

hossboss said:

Hi I have a 1998 Landrover Discovery V8i (LPG) converted

Over the last couple of weeks I have had a problem with the coolant.
The Vehicle tends to pressurize and forces coolant out of the cap on the header tank. I have tried to solve my problems by having my car checked at a garage to see if the head gasket`s have gone, but both garages have told me that they have not gone.

Any help or input would be much appreciated many thanks.

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Symptoms are pointing to Head Gasket Failure. Do you know what tests the garage did? It might be worth getting a compression gauge and doing your own compression test. Also, take the plugs out and have a look at them, are one or two (or more) plugs looking a bit cleaner than the others?

Another possible indicator of HGF is lots of condensation out of the exhaust on a cold morning but this is not absolute because V8's make a lot of condensation anyway but if you can make your own fog, there may be a problem.

Another thing you may wish to bear in mind is that when the cooling system is pressurising it puts a lot of strain on all your hoses. Check all your hoses and make sure they are all still properly seated etc and the clips are tight, also check them for signs of fatigue. It is not unknown for hoses to be blown off under high pressure, this will dump all your coolant and if you don't notice you could cook your engine. Another problem with the pressurisation is that if there is enough pressure to blow the coolant out of the cap, it can then run down on to the front off side brake disc, I've had this happen on my RRC it is not nice when you step on the brakes and find you can't hold the car straight because you've only got brake force on 1 front brake.

Hope that helps ya.

Hi thanks for all your input I have been putting it out of my mind that its the head gasket as I am not looking forward to having the pay to have the work done the car has cost me that much in the last year I just cant afford not to get it fixed but in for a penny in for a pound. Looks like i will be having my head gasket`s done.

classic kev said:

Symptoms are pointing to Head Gasket Failure. Do you know what tests the garage did? It might be worth getting a compression gauge and doing your own compression test. Also, take the plugs out and have a look at them, are one or two (or more) plugs looking a bit cleaner than the others?

Another possible indicator of HGF is lots of condensation out of the exhaust on a cold morning but this is not absolute because V8's make a lot of condensation anyway but if you can make your own fog, there may be a problem.

Another thing you may wish to bear in mind is that when the cooling system is pressurising it puts a lot of strain on all your hoses. Check all your hoses and make sure they are all still properly seated etc and the clips are tight, also check them for signs of fatigue. It is not unknown for hoses to be blown off under high pressure, this will dump all your coolant and if you don't notice you could cook your engine. Another problem with the pressurisation is that if there is enough pressure to blow the coolant out of the cap, it can then run down on to the front off side brake disc, I've had this happen on my RRC it is not nice when you step on the brakes and find you can't hold the car straight because you've only got brake force on 1 front brake.

Hope that helps ya.

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Hi you sound like the kind of person that knows what they are talking about can you recommend what I should also have done when I am having the head gasket done.
Many thanks

hossboss said:

Hi you sound like the kind of person that knows what they are talking about can you recommend what I should also have done when I am having the head gasket done.
Many thanks

Click to expand...

Aye, Check fer slipped liners

hossboss said:

Hi you sound like the kind of person that knows what they are talking about can you recommend what I should also have done when I am having the head gasket done.
Many thanks

Click to expand...

There are lots of things I would suggest to check/look at/replace but if you are not doing the work yourself, it will cost a small fortune.

Sensibly,if you are popping the heads off I would be looking at the condition of the cam followers (hydraulic lifters) and also the cam shaft. Look at the tops of the pistons and cylinder bores, check for overall condition and then remove soft carbon from pistons and de-glaze cylinders if necessary.

When the heads are off, remove all the valves and then give them a clean up and then lap the valves in. Replace valve stem oil seals.

Check inlet and exhaust ports for clearance around gaskets - some heads have been known to be very poor and some porting has been required to get them to where they should be to ensure the gaskets are not actually blocking the ports.

Carefully and thoroughly clean the air inlet system - ram housing, plenum, throttle linkages, throttle disc. Make sure everything is very clean and all mating faces are smooth. I might also check the heads for warping/cracks or other visible defects.

If you wanted to go a bit further, you could consider popping off the timing cover but that is another story entirely.

Sounds scary I know but hopefully a good indy would at least look at what you would do if you did the job yourself but you can never have any guarantees.

Lastly, I would expect air and oil filters to be replaced. Fresh oil and fresh anti-freeze. It would also be sensible to have the radiator flushed and checked out to ensure it isn't blocked externally (as in crud in the fins).

Hope that gives you some ideas. To do a head gasket job including grinding valves, I would anticipate a day and a half (max) for 1 man in a well equipped workshop assuming all necessary parts are in stock.

Many thanks I work for Euro Car Parts and my first job Today is to get a Quote for all the parts I am going to need for the Job I have a couple of mates with there own workshop they are not looking forward to doing the Job but will do it for me at Mates Rates so it looks like the Job is on some time in the next month.

Thanks for replys, have flushed complete cooling system, replaced thermostat, replaced thermostat housing gasket, bled the cooling system, and fingers crossed no more coolant out through the header tank cap.

Hi looks like you were right bled cooling system and fingers crossed all is ok car heater working very well and no loss of coolant many thanks

Hi turns out i had not bled the cooling system had an air lock but all is well now.
The new Thermostat has helped with the heating during the last 2 weeks all`s well and ends well many thanks for your input..

allways been very easy to over fill rover v8s