205 xs overheating problem

macaroni · Post by **macaroni** » 26 Jan 2006, 22:39

After fitting a new gearbox and my 4-2-1 manifold, my xs has developed another problem.
I think I know what the answer is, but I would like a 2nd, 3rd or even 4th opinion...

The engine gets very hot, but the heater is ice cold and the thermostat opening doesn't help. The radiator is hot, but the bottom hose is cool. The water in the expansion tank is also cold.

I have flushed the rad and engine, so no obvious blockages, replaced the thermostat and checked the water pump. All seems OK.

I guess it is either a head/gasket problem, but there is no emulsion in the oil, it doesn't lose water and I can't see why the heater wouldn't get hot.

Anybody got any other suggestions before I whip the head off?

Cheers,

Antony

stevieb · Post by **stevieb** » 27 Jan 2006, 00:57

Sounds like an air lock to me.

Does it have a bleed screw in one of the "higher" coolant hoses in the engine bay? If it does, try opening it up with the engine cold and see if you get a dribble of coolant. If it's dry, then you know it's definitely an air lock, and just needs bleeding.

I imagine if the air lock reaches as far as the water pump then no water will flow at all...

pugxpert · Post by **pugxpert** » 27 Jan 2006, 07:49

sounds like air as well,unclip coolant expansion bottle from its holder and lift it up and tie it to the bonnet.loosen brass bleed screw on thermostat housing,loosen bleed screw on heater pipe,remove cap on top of radiator on left hand side.fill through expansion bottle hanging off bonnet untill water comes clear out of all bleeders,tighten all bleeders.run up engine with expansion bottle hanging from bonnet with the cap off this will allow any trapped air to escape,run up untill fan has cut in and out then refit bottle in its holder,works everytime,same procedure on old 505's.the other thing you say you have checked water pump have you phisically taken it out? had a few where the impellor falls off inside.

macaroni · Post by **macaroni** » 27 Jan 2006, 08:25

Thanks for the tips guys.

I have run it for a good 10 minutes, until it almost boiled, with both bleed screws open and only air came out. No water at all. All time, the expansion bottle was full, with cold water.

I too suspected a snapped water pump impeller and removed the pump last night and it is perfect. No play or leaks.

I think I will concentrate my next efforts on the radiator before tackling the head.

Although, the only thing that would cause the heater pipes to remain cold is an air lock, so maybe it is that! Aargh!!

pugxpert · Post by **pugxpert** » 29 Jan 2006, 14:27

did you take expansion bottle out and hang it up high?

macaroni · Post by **macaroni** » 29 Jan 2006, 15:40

OK, I drained the cooling system. Hung the expansion bottle high and filled it up till rad overflowed.

I undid the bleed screws and ran the engine. After a few minutes the bleed screws starting pissing water and the heater began to get hot - Bingo I thought. Then all of a sudden, the bleed screws dried up, heater got cold and the temp gauge went sky high.

The expansion bottle filled right up and was under a lot of pressure, but the top rad hose was cold.

I have checked the thermostat, water pump and flushed the rad and the block.

It kind of points to the cylinder head, but that wouldn't explain the heater being cold.

I am perplexed! Any other ideas gratefully received.

pugxpert · Post by **pugxpert** » 29 Jan 2006, 16:05

i usually fill up untill water comes out of bleeders with the engine not running then close off all bleeders then run up engine with cap off expansion bottle untill fan cuts in if you run it up with cap on any trapped air in system cannot escape

macaroni · Post by **macaroni** » 29 Jan 2006, 16:20

OK, I can try that.

Have you ever known air to get into the system without anything being disturbed?

My symptoms appeared just after I fitted a new exhaust manifold and I am sure that must be just a co-incidence.

pugxpert · Post by **pugxpert** » 29 Jan 2006, 18:44

no not really,you can get something called a block tester which sits on your expansion bottle and you run up engine if you see bubbles and the test fluid changes colour that indicates a headgasket failure,does the car boil up if you leave cap off bottle? or is it just air being pushed out as you run it up and can you feel top hose and see if it is hot when thermostat opens? when stat opens you may find loads of air comes out then as this path is blocked untill it opens.

macaroni · Post by **macaroni** » 30 Jan 2006, 16:41

The top hose does get hot when the stat opens, but if I left the top of the expansion bottle off, water would flood out. It doesn't look like it is full of bubbles, just pressure. It definitely isn't boiling up as the water is stone cold!

It really does feel like some path is blocked, but I can't fathom what. Or maybe I am just avoiding the ineviable removal of the head.

pugxpert · Post by **pugxpert** » 30 Jan 2006, 17:18

if you crank engine over with ignition coil disconected so it does not start do you see water bubbling as you crank it over? if you do its head off i'm affraid.

pugxpert · Post by **pugxpert** » 30 Jan 2006, 17:19

if you crank engine over with ignition coil disconected so it does not start do you see water bubbling as you crank it over? if you do its head off i'm affraid. when you ran it up with cap off did it just bubble or did it get to the point where water was spewing out of bottle?

macaroni · Post by **macaroni** » 30 Jan 2006, 19:56

I will try cranking with the coil off, but when I ran it with the cap off, it just welled up and overflowed, it didn't seem to bubble at all.

I used to be a mechanic and my Dad still is and I have seen loads of HGFs, but this just doesn't seem like one.

macaroni · Post by **macaroni** » 03 Feb 2006, 08:34

Well, after all that it was a head gasket problem. There was a rusty split in it, just outside of number 1 piston.

Thanks for all your suggestions chaps.