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Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

Hello and thanks for all the advice so far.

After removing the cylinder heads and skimming, refitting, chucking the thermostat, flushing the radiator and hoses, checking the viscus fan and replacing the two electric cooling fans the engine still boils and spits the coolant out on the ground through the header tank vent cap after only a couple of miles. I was not convinced with the finish of the skim job but the company does it all the time for the local land rover agency so trusted them. could not see evidence of cracking of the heads anywhere, on replacement I replaced the streach bolts and torqued religously.

There are bubbles through the header tank when topped up to the neck and the engine run, eventually it kicks the water out while idling, could the bubbles be residual air or is this a dead cert the head has gone again? 15 thou skin last time, i'm informed there is a ridge in the combustion chamber indicating limit for rework, but all I can see is a small flat area the size of an old sixpence but it seems too far to be the indicator in question, anyone know a dimensional limit? all further advice regardin this problem very much appreciated. Many thanks, Mike.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Collos25

By the sound of it you need new heads,there is the other alternative and that is the block has imperfections .

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Peter.N.

How many miles has it done? If its a lot, could need a new radiator. If it is actually boiling rather than being pushed out by combustion pressure it will be a cooling system problem not the engine..

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - madf

Try flshing the cooling system first... as a cheaper alternative. On eof the proprietary flsuhing agents will do. You MAY have silted up waterways as it is an aluminium block and they corrode if you don't use the correct antifreeze.

You did check the antifreeze was of the correct strength? And not past its sell by date.

You checked the thermostat , radiator etc so it's not them.. If it's bubbles, sounds like exhaust gasses. Try a sniffer test to check for gas in the water.

Edited by madf on 29/07/2010 at 17:36

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Collos25

Any problem caused by the above will make it run hot not spit water out.In fact none of the above will cause your problem .

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

Try flshing the cooling system first... as a cheaper alternative. On eof the proprietary flsuhing agents will do. You MAY have silted up waterways as it is an aluminium block and they corrode if you don't use the correct antifreeze.

You did check the antifreeze was of the correct strength? And not past its sell by date.

You checked the thermostat , radiator etc so it's not them.. If it's bubbles, sounds like exhaust gasses. Try a sniffer test to check for gas in the water.

Thanks, for the advice, the coolant was very green, had been topped up just before i bought the car cheap with a view to an inexpensive repair to the engine and a cheap second car, I'm actually working and living with my brit family in Oman so anti freeze not required, however the water quality is poor and could as you say be corrosion. How do you do a sniff test? there is not a lot of gear out here, would holding a flame to the bubbles be a sensible suggestion, goes out, exhaust, pops mixture, just a thought, still trying to find skim limits. heads been off twice, thinking of skimming again with better finish in case ridges causing blow by the gasket. Just for info, the water seems to heave out the expansion chamber after running for a few minutes, no evidence of water out the exhaust as steam or leqaks from the side of the block, cheers, Mike.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Collos25

That normally means it has gone between two water ways.You need the correct equipment to do a sniff test.If the block is not ok it does not matter how many times you shave the head the problem will stay.Don,t forget if you keep shaving the head you will increase the compression ratio unles you compensate with a thicker head gasget.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

Hello Andy, does this mean, if there is corrosion in the block and the water is not circulating and cooling because it's effectively taking a shortcut, or do you mean the gasket has blown between the head and the block? if the former is the case that would write the car off as exchange engines are more than the car's worth, cheers, mike

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

How many miles has it done? If its a lot, could need a new radiator. If it is actually boiling rather than being pushed out by combustion pressure it will be a cooling system problem not the engine..

Done 117,000 Kilometers so Iguess thats about 80 K miles, in Oman with poor water quality, there was lots bof coolant in the rad, yes the water heaves out of the radiator if run with cap off, laterly producing smallish bubbles, wondering if residual or gasses, pressurises big time if cap on just vents out the header tank, any ideas of flush agent to use? Cheers, Mike.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Dave N

They're well known for the liners shifting in the block. No cure except a new engine.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Dave N

They're well known for the liners shifting in the block. No cure except a new engine.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

Hi, bad news then, how do i check for the liners having moved, or is there no check? like to try everything before throwing it away.

Thanks, Mike.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Collos25

You really need the engine out ,

I meant the gasget has blown between a cylinder and a water way but I still think if the head was shaved properly the problem is in the block either the liners have shifted or there is a crack but you need both testing .There used to be plenty of companies in the emirates who do block repairs but you are stabbing in the dark without the full tools and test apparatus,you cannot keep on building up and stripping down an engine to get back to square one.I would have thought there are plenty of back street garages who would fit a a replacent chrysler or chevy engine or even repair yours. Second hand cars used to very cheap is that still the case I bought a Caddie for peanuts and ran it for two years in Saudi.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

Andy, thanks for all that, much appreciated.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Peter D

You need to establish if the bubbles are combustion products as Andy has pointed out, or is it actually boiling. Has the water pump been checked. Regards Peter

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

Hello peter, no, the water pump has not been checked, I think that would be a good idea, what sort of defect could be evident on removal that might cause such a problem?

Can the pump be tested by cranking the engine and checking the output, or is it a removal?

Regarding the liners moving in the block, I did have a very good look at the top of the block on removing the heads,( both times) and all looked well, but would you see obvious signs of movement?

Thaks so far, and regards, Mike.

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Peter D

The simpliest test is to remove the pump output coolant pipe and crank the engine to see if it forced the water out. IF not then pump removal time. Do you know if the pump on that engine has a composite propeller rether then case metal. The former have a happit of letting go of the shaft. Have you had the header tank sniffed, or coolant checked for combustion products. Regards Peter

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - Collos25

The car is in Oman

Discovery 3.9 1999.petrol. - Discovery 3.9 petrol engine boiling - strickjumpers

Thanks everyone for all the good advice, i'm currently 1k miles to the south of the car and won't be back til next saturday but at least there are a few ideas to be getting on with. my wife returns from summer holidays in the uk on 15th so can hand carry bits for repair. no chance of sniffing anything out here as equipment next to non existant.

where and what number is the best source of bits if an improvement on paddocks, cheers, mike