High temperature, little pressure, loss of water..
Discussion
...what does it all mean? As a continuation of the no pressure in the header tank I have found the pre-mentioned problems. I reckon it has to be the water pump? What do you guys think? No obvious leak from any of the tubes or piping. Basically it is okay until you hit traffic and then it goes mental! It feels like a worn water pump to me?
Dave,
I don't wan't to worry you and I will say I'm not a mechanic but If it was me I would be thinking the worst case senario.
Could this be a blown head gasket or cracked head? It seems to me the water must be going somewhere and if there are no leaks?
I've had a gasket go on me after a car I used to have overheated but that was quite noticible as it would stop after about a mile and there was 'mayonaise' in the oil. I've also had a leaking radiator on another car, this too was quite easily seen as when I parked up for a while it would have a pool of coolant under it when I returned.
You could try putting a bit of kitchen roll over the exhaust when the engine has warmed up, it will disintergrate if there is water comming out of it, or do a complete oil and coolant change to see what comes out.
If your only loosing a small amount of water it may still be a small leak you haven't found yet in a pipe or from the waterpump?
Good luck, I may be way out on this as I say I'm no mechanic.
I don't wan't to worry you and I will say I'm not a mechanic but If it was me I would be thinking the worst case senario.
Could this be a blown head gasket or cracked head? It seems to me the water must be going somewhere and if there are no leaks?
I've had a gasket go on me after a car I used to have overheated but that was quite noticible as it would stop after about a mile and there was 'mayonaise' in the oil. I've also had a leaking radiator on another car, this too was quite easily seen as when I parked up for a while it would have a pool of coolant under it when I returned.
You could try putting a bit of kitchen roll over the exhaust when the engine has warmed up, it will disintergrate if there is water comming out of it, or do a complete oil and coolant change to see what comes out.
If your only loosing a small amount of water it may still be a small leak you haven't found yet in a pipe or from the waterpump?
Good luck, I may be way out on this as I say I'm no mechanic.
It sounds to me like you need to get the system pressure tested. If you have not got the necessary equipment (or can't cobble something together) I would have thought cost of getting a garage to do it is minimal. You do hear stories about leaks only occuring when hot, but if your problem is that noticeable I would have thought it would be picked up.
Water pump is really only an impeller, i.e. it isn't a 'pressurising' pump, just helps the water flow round. Way back in the good old days, engines just used thermosyphon effect to move the water round. The pressure is created by the system being sealed, and the water getting hot and expanding. Because this creates pressure, it increases the specific heat capacity of the water and allows it to get hotter without evaporating.
Normally, a water pump only fails insofar as the shaft bearings are overloaded by e.g. an overtight fan belt, or the internal bearing water seal fails due to old age or overheating. Then water gets into the shaft bearings and failure is imminent. This is when you get water dribbling from the drain hole in the pump casting.
So, if the pump is OK, you have to have some leak to be causing the system not to pressurise. Looking at the V8 waterways, it's 'unlikely' it would be losing into a cylinder. If it could, then you'd have the reverse effect, i.e. combustion gas in the water jacket and lots of puffing from the expansion tank!
I've had multitudinous leaks on my car: bypass hoses behind the water pump; heater hoses behind plenum chamber; split header tank; assorted pipe unions around the engine bay. It could even be the seals on the two coolant caps. I made a simple pressure tester using an old rad cap and was able to rectify most leaks in one afternoon, without getting scalded!
All this is not to preclude head gasket failure, of course: I have heard of people having coolant dye test to eliminate head gasket; test was negative and yet replacing the head gasket fixed the fault! Bizarre.
W.
Normally, a water pump only fails insofar as the shaft bearings are overloaded by e.g. an overtight fan belt, or the internal bearing water seal fails due to old age or overheating. Then water gets into the shaft bearings and failure is imminent. This is when you get water dribbling from the drain hole in the pump casting.
So, if the pump is OK, you have to have some leak to be causing the system not to pressurise. Looking at the V8 waterways, it's 'unlikely' it would be losing into a cylinder. If it could, then you'd have the reverse effect, i.e. combustion gas in the water jacket and lots of puffing from the expansion tank!
I've had multitudinous leaks on my car: bypass hoses behind the water pump; heater hoses behind plenum chamber; split header tank; assorted pipe unions around the engine bay. It could even be the seals on the two coolant caps. I made a simple pressure tester using an old rad cap and was able to rectify most leaks in one afternoon, without getting scalded!
All this is not to preclude head gasket failure, of course: I have heard of people having coolant dye test to eliminate head gasket; test was negative and yet replacing the head gasket fixed the fault! Bizarre.
W.
Well the water and the oil still seem to be independant of each other. There is no brown white bits in the oil and the no oil in the water. This gives me hope that it is not the head gasket. Although it does look a little damp around an area of the water pump. My best guess is that it is the pump seal. I reckon this could be why the pressure is down and water loss has occurred....which would lead to a high temp. Does all that sound logic? Or am I really clutching at straws?
quote:
It could even be the seals on the two coolant caps.
Mine only has one on the expansion tank! I figure this is unusual as all the others I have seen have a second one in the metal pipe that runs across from the front of the engine to the top of the radiator, I have a bolt in the top of the pipe (at the engine end)for bleeding instead, and a pipe going into it about half way down that goes off to the expansion tank and the engine.
Does anyone elses have this setup?
It does not look the work of billy bodger to me but the pipe does not look 15 years old either.
GF.
I don't think I've ever seen the same water plumbing on any 2 wedges!
I guess it's always been a trial and error thing to combat air locks and overheating.
I'd say, if it works, leave it alone!
My 390 has two caps as described above; sometimes the swan neck is low on water, but it seems to correct itself.
On thing I have been pondering: there's a water feed to the throttle body. Surely a wedge needs intake heating like Michael Jackson needs a monkey wrench?
Ian
I guess it's always been a trial and error thing to combat air locks and overheating.
I'd say, if it works, leave it alone!
My 390 has two caps as described above; sometimes the swan neck is low on water, but it seems to correct itself.
On thing I have been pondering: there's a water feed to the throttle body. Surely a wedge needs intake heating like Michael Jackson needs a monkey wrench?
Ian
following on from wedg1e's comments about the system pressurising when hot, this is why that leaks are nt always apparent when hot as water turns to steam ie vapour and evaporates before you can see it, So if you can pressurise the system when cold, Using an old radcop fitted with a tyre valve, a foot/ bike pump can get 10 psi in the system and the rad/pipes will do a niagra falls impression allowing you to pin point the leaks in the numerous joints.. My heater hoses ended up being the culprit they looked fine from the outside but bend them and the literally fell apart due to the rubber being brittle due to promimity to the engine. hope it helps ..
quote:
Well I have ordered a new water pump from David Gerald, so I will give that a go at the weekend. I will keep you guys update with any progress...cheers.
Make sure it is the right one as there have been several different variations including the pulley mount. Chcek it is an exact replacement before fitting. Last thing you want is engine without water pump and the new one don't fit.
Steve
www.tvrbooks.co.uk
Couple more things, memory jogged by reference above to header tank connections: firstly, my original header tank split adjacent to the uppermost hose coupling! Couldn't repair it no matter what I tried: GRP, Araldite, soldering iron. Ended up getting another tank (from Tick Over darn Lunnen way!).
Secondly: if Michael Jackson DOES need a monkey wrench, does Peter Gabriel need a sledgehammer?
;-)
Ian
Secondly: if Michael Jackson DOES need a monkey wrench, does Peter Gabriel need a sledgehammer?
;-)
Ian
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