The Triumph Dolomite Club - Discussion Forum

I have been fighting a slow loss of coolant, leave it for a couple of weeks on the level drops above the thermostat and there was liquid on the block. I suspected the inlet manifold head joint and have been trying to seal this. Resorting to leak stop, which seems to have slowed it down.

Being a pessimist, I assumed the worse and thought head gasket. However no smoke from exhaust, no water in oil and no bubble in expansion tank when running. So can I rule that out?

To be honest I don't understand how the expansion tank works. It sits lower than the engine, so why doesn't the coolant just drain out under force of gravity? How does it keep the system under pressure when it has a drain at the top? Oh and can I use the brass tank off an MG Midget as I am at the moment or will that not work?

You need one of those "sniffers" which detect exhaust gasses in the coolant and change colour. The only other things I can think of are the expansion bottle cap (should be 13psi IIRC) and the core plugs so they might be worth checking even if you just eliminate them from your diagnosis.

My car (TR7 engine, so close enough) had a weep along the inlet side of the head/block join. Slow, but there.
Like you, no other symptoms. So it could be gasket. Assuming you have had the inlet manifold off and checked/new gasket etc etc. and obviously you are certain not the water pump.

As to the header, height won't matter. The takeoff at the top, just under the car, is after the sealing washer so unless the system over-pressurises and forces teh cap seal up/open, no problem. And when cold, the water does not flow out because that would create a vacuum in the engine, so the 14psi of air pressure we have at sea level keeps that from happening. Don't worry about it! The tank should work fine as long as the cap seals ok.

cliftyhanger wrote: ↑Fri Mar 22, 2019 1:15 pm My car (TR7 engine, so close enough) had a weep along the inlet side of the head/block join. Slow, but there.
Like you, no other symptoms. So it could be gasket. Assuming you have had the inlet manifold off and checked/new gasket etc etc. and obviously you are certain not the water pump.

As to the header, height won't matter. The takeoff at the top, just under the car, is after the sealing washer so unless the system over-pressurises and forces teh cap seal up/open, no problem. And when cold, the water does not flow out because that would create a vacuum in the engine, so the 14psi of air pressure we have at sea level keeps that from happening. Don't worry about it! The tank should work fine as long as the cap seals ok.

It could be the pump but the water on the block appears to be coming from above it. So it is either the head gasket or the inlet gasket.

The rate of loss does seem to be reducing, so I am hoping the leak stop may have cured it.

Irritating because apart from that there isn't a leak on the car, very un-Triumph like.

The first job is to remove the inlet manifold and REPLACE the gasket. USE SILICON sealer around the water gallery at the front. I've given up on trying to fit them dry on Sprint engines. The second thing is, while it's off, check and replace if needed, the rubber O rings on the bypass pipe that goes between the manifold and the water pump housing.

Stop leak, Radweld, Barrs leaks etc are short term bodges that will inevitably do more harm than good, bunging up the radiator core and leading to overheating. Do it properly and do it once!

Steve

The plastic bottles do stretch so the caps pressure isn't a given value. You can test by pressurize the system with a pressure gauge inline to check. Some caps open at a very low pressure leaving coolant out the overflow under normal driving conditions.

Jeroen

Carledo wrote: ↑Fri Mar 22, 2019 8:13 pm The first job is to remove the inlet manifold and REPLACE the gasket. USE SILICON sealer around the water gallery at the front. I've given up on trying to fit them dry on Sprint engines. The second thing is, while it's off, check and replace if needed, the rubber O rings on the bypass pipe that goes between the manifold and the water pump housing.

Stop leak, Radweld, Barrs leaks etc are short term bodges that will inevitably do more harm than good, bunging up the radiator core and leading to overheating. Do it properly and do it once!

Steve

Don't think there is much danger of that, it has a brand new Saab radiator and the whole cooling system has been cleaned out. Not sure what it could block, if used as directed.

Already tried silicon, didn't work, did end up with a mess around the inlet water gallery. To be frank I am more worried about bits of silicon making there way into the system than stop leak.

cleverusername wrote: ↑Fri Mar 22, 2019 10:09 pm

Carledo wrote: ↑Fri Mar 22, 2019 8:13 pm The first job is to remove the inlet manifold and REPLACE the gasket. USE SILICON sealer around the water gallery at the front. I've given up on trying to fit them dry on Sprint engines. The second thing is, while it's off, check and replace if needed, the rubber O rings on the bypass pipe that goes between the manifold and the water pump housing.

Stop leak, Radweld, Barrs leaks etc are short term bodges that will inevitably do more harm than good, bunging up the radiator core and leading to overheating. Do it properly and do it once!

Steve

Don't think there is much danger of that, it has a brand new Saab radiator and the whole cooling system has been cleaned out. Not sure what it could block, if used as directed.

Already tried silicon, didn't work, did end up with a mess around the inlet water gallery. To be frank I am more worried about bits of silicon making there way into the system than stop leak.

Stop leak is a temporary fix and masks the real fault and is no substitute for a proper repair,stop leak is often used by back street car dealers who give you a 3 month warranty ( about as long as stop leak lasts !! ) and then shrug their shoulders when you bring your leaky car back, take a look at this and make your mind up
https://www.youtube.com/watch?v=K0AdK_gEX88

mahony wrote:

cleverusername wrote: ↑Fri Mar 22, 2019 10:09 pm

Carledo wrote: ↑Fri Mar 22, 2019 8:13 pm The first job is to remove the inlet manifold and REPLACE the gasket. USE SILICON sealer around the water gallery at the front. I've given up on trying to fit them dry on Sprint engines. The second thing is, while it's off, check and replace if needed, the rubber O rings on the bypass pipe that goes between the manifold and the water pump housing.

Stop leak, Radweld, Barrs leaks etc are short term bodges that will inevitably do more harm than good, bunging up the radiator core and leading to overheating. Do it properly and do it once!

Steve

Don't think there is much danger of that, it has a brand new Saab radiator and the whole cooling system has been cleaned out. Not sure what it could block, if used as directed.

Already tried silicon, didn't work, did end up with a mess around the inlet water gallery. To be frank I am more worried about bits of silicon making there way into the system than stop leak.

Stop leak is a temporary fix and mask the real fault and is no substitute for a proper repair,stop leak is often used by back street car dealers who give you a 3 month warranty ( about as long as stop leak lasts !! ) and then shrug their shoulders when you bring your leaky car back, take a look at this and make your mind up
https://www.youtube.com/watch?v=K0AdK_gEX88

And it cloggs waterway's, heater matrix etc. etc. etc.

Jeroen

OK, new plan. I have a spare inlet manifold, I am going to find a machine shop to get the mating surface skimmed flat and then fit that. Hopefully that will solve the problem.

Oh and it is definitely the inlet manifold gasket, I stuck my fingers down there and the gasket is damp.

Use some silicon on the bypass tube as well or you may end up with another leak.