(V6) Circulation problem

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bukko

bukko

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The car has been running hot and the header tank was cracked, so I replaced it.

I didn't drain the system, just what was in the original bottle, then topped it up after replacing.

Went for a short drive and checked the bottle, which was shown a LOT more coolant than it had before.
Quick blast up the motorway and back, then when I got home as I stopped there was a puff of steam from under the bonnet at the bottle corner.
Switched off, bottle bubbling away, gurgling noises from where the bottom radiator hose meets the engine (not sure what bit that is).

When I touched the bottom radiator hose it was cold. I'm thinking airlock.
The only bleed point I can find is on the heater return hose. Are there any more or is that it?
 
Hmm apparently that's it!
Seems a bit daft being so near to the coolant reservoir.

I can't find a link to a bleeding/re-filling procedure - anybody know of one?

[edit]
Found this - will try it tomorrow.
[/edit]
 
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The KV6 is known to a bit of a swine to get the air out the cooling system. The best way i'v found is the have the car pointing down hill. The air bleed is then at the highest point. The expansion tank needs to be to be filled so there is only a small air space at the top with the cap fitted. Then run the engine and open the air bleed screw, as the warms up the air is pushed out, this often needs doing a couple of times to clear most of the air out the system. The remainder will come out in use over the following few drive cycles.
 
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Good tip! (Again!)

I'll put the back wheels on ramps before I do it.

Some people say leave the cap off and top-up as the level drops - is this right?

The thermostat was allegedly replaced when the housing was changed about a year ago and the temperature problem has been since then, so I'm hoping that's ok and the issue is purely an airlock.
 
bukko said:
Good tip! (Again!)

I'll put the back wheels on ramps before I do it.

Some people say leave the cap off and top-up as the level drops - is this right?

The thermostat was allegedly replaced when the housing was changed about a year ago and the temperature problem has been since then, so I'm hoping that's ok and the issue is purely an airlock.
Click to expand...

I find it bleeds better if the cap is fitted as there is more pressure to force the air out once the engine is hot but you could try the cap off method. If you do it the hot way just remember the water is really really hot!! Thermostats do fail which is the reason I changed the engine. I did the HG's and fitted a new stat but that failed within 1500 miles which popped another HG :( not knowing if the engine was prone to popping them I changed the engine , only discovering the failed stat when I pulled the engine apart to find out what had failed!! Next coolant change I'll be fitting the Kisar alloy stat.
 
Just for reference, this is what you get (from XPower forum).
Looks much more robust than the original!
 

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bukko said:
Just for reference, this is what you get (from XPower forum).
Looks much more robust than the original!
Click to expand...

That's the Kieser kit :) it's well made although getting hold of it is a bit interesting!! On the plus side the engine runs around 10°C cooler with it which can only be a good thing.
 
Tried bleeding the coolant several times today.
No noticeable air was released though.
No coolant seeps out until it gets hot - does this mean the thermostat is working?
The bottom radiator hose still stays cold.

One thing I did notice though was that when I reconnected the heater hoses a while ago I got them the wrong way around, so the return hose is at the bottom.
I don't think this should make any difference to the circulation, apart from making bleeding a bit more awkward.
The heater still gets hot anyway.
 
bukko said:
Yes - should I not?
Click to expand...

Somebody queried this the other day. I have always set the heater to hot but coolant passes thru the matrix constantly with the flaps controlling where it goes and how much etc. Begs a question??
 
Tried to bleed it yet again this morning. No air from the bleed screw, just hot coolant.
But the bottom radiator hose is still cold. Sounds like a gurgling from where it goes into the thermostat.
Coolant is being circulated back into the reservoir via the expansion pipe.
I assume this all means the coolant pump is working ok? Not sure how to test it otherwise.
Not sure how the thermostat works, but maybe it's allowing flow except from the radiator - is this possible?

Hmm there's a thermostat bypass pipe - so apparently yes. Wonder what would happen if I blocked that off?

Was thinking about making up another bleed point to go at the top of the bottom rad hose, if I can find the bits.

Ah well it's not fatal - yet... :confused:
 
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bukko said:
Tried to bleed it yet again this morning. No air from the bleed screw, just hot coolant.
But the bottom radiator hose is still cold. Sounds like a gurgling from where it goes into the thermostat.
Coolant is being circulated back into the reservoir via the expansion pipe.
I assume this all means the coolant pump is working ok? Not sure how to test it otherwise.
Not sure how the thermostat works, but maybe it's allowing flow except from the radiator - is this possible?

Hmm there's a thermostat bypass pipe - so apparently yes. Wonder what would happen if I blocked that off?

Was thinking about making up another bleed point to go at the top of the bottom rad hose, if I can find the bits.

Ah well it's not fatal - yet... :confused:
Click to expand...

The stat is a bypass stat that contains a Pressure Release Valve that should open at higher revs. It sounds like the thermostat has failed to me. It should allow coolant to flow through the heater and coolers until normal operating temp. When the engine is really hot then it shuts off the heater to force all the coolant through the rad. Sometimes it fails blocking both flow paths. This is what killed my last engine so be careful ;)
 
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bukko said:
Was just thinking - could it be the radiator?

£66 for a new one on Ebay...
Click to expand...

Don't waste your money on a rad. Unless you have put rad weld in it's unlikely to be blocked. It's easy to flush anyway ;) it's screaming failed stat to me!! When was it changed! I change mine with the coolant to help improve reliability!!
 
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