Coolant loss

[taylormj4]

Hi all,
Experience / advice required please:

Went to drive home from work few days ago and found the front windscreen fogged up and took ages for the blower to demist it. Then realised that cold air still coming out after idling for 5 minutes. Engine temperature up to around 75degrees though.

Wiped screen by hand and then drove home and noticed engine temperature rising alarmingly higher than normal - approaching 100degrees at one point. This lowered when cruising at speed and using lightest throttle possible to accelerate (cold evening luckily) but then rose again once down to 30 (requiring cooling-off stops).

Haven't had time to investigate yet due to appauling weather but I'm guessing major coolant loss is the problem?

Does anyone know the weak spots in the cooling system that are likely to have failed?

Cheers,
Matt

[andy-w]

Radiator leak/split...seals gone in water pump...hose come off????

[That Daddy]

Taylor the coolant level needs checking straight away,it sounds like you have air in the system due to low coolant,please dont continue to use like this,when the level drops the 1st thing to suffer is the cylinder heads the hottest part of the cooling system,top it up and check for leaks,good luck.

[spend]

Check for mayo in oil filler cap (headgasket failure Not so Common, just sensible first check)
Expansion cap faulty
Rad needs recore/repair
Bad Seal on Pipe Connector (even burst pipe) + check pipes into heater matrix
Drip from water pump seal
Heater matrix

Really after checking first, just refill, bring up to temp and look for leaks. Kitchen roll is a useful diagnostic aid ;-)

Dave

[ekim]

Had the same thing on mine about two weeks ago, ran it up in the drive and just kept my eye on everything. When it got the full temp (just b4 the fan comes in) it started to drip from the little holde on the water pump (visable from the drivers side). put a new pump on (cost about £80) and all side dry again now

[taylormj4]

Update:

thanks for the advice.

Filled the coolant system back up with antifreeze/water mix (50%/50%) according to owner's manual method. Needed around 5 litres to top up. Started engine, no leaks.

Engine reaches normal temperature, fans cut-in and out Ok. No leaks apparent. Heater working again. Take it for a run and no overheat - if anything, running temperature is slightly lower than normal, between 70 and 75 degrees C. Normally nearer 80C.

Any ideas. Steve Heath's book mentions that the expansion tank pressure cap can become faulty and leak coolant. I've lost 5 litres here somewhere? Hopefully, the engine is not burning it due to faulty head gaskets!

Am I correct in thinking, I'm Ok to continue driving and just keep an eye on the coolant level more regularly? If the heater is working, there must be coolant in the engine, right?

Cheers,
Matt

[poorpeet]

Not much else you can do short of stripping the motor to look for a problem that may not exist.
I take it you have checked, and will keep checking, the engine oil for signs of water?
Maybe the expansion tank cap was slightly loose & was allowing a little vapour past over time?
Just keep a close eye on it for a while.

[tvrbob]

Once the expansion pot is empty a slow/small leak will suddenly become a big loss of coolant. When the expansion pot is too low the natural expansion and contraction of the coolant will start to draw air into the system. Because the expansion pot is set low in the car the entrained air cannot easily find its way back so it will circulate in the system. The big problem with this is that any air pocket hitting water pump impeller will stall the forced circulation. Within a few seconds of this happening the water in the block will boil and thereby pressure the system beyond the cap pressure so large quantities of coolant will be ejected through the pressure cap.

The important thing is to ensure the system is primed, i.e no air in the system. You won't achieve this through topping up the expansion pot. The only way to prime these systems is through the high point on the swirl pot. With the engine off, undo the brass screw and check for coolant level. Coolant should be brimming the swirl pot; if not then you still run the risk of a forced circulation stall and subsequent ejection of coolant.

[spend]

VW Expansion caps are only a few quid + its worth having a spare anyway.....

Dave

[taylormj4]

Hello,
update:

I am loosing coolant but have no idea where from. When up to temperature and after driving to work, inspection finds no steam leaking from the radiator, no leaks from the water pump, nothing running out from the expansion tank.

Pants!

More annoyingly, a leak INTO the car into the driver's footwell has also started. I don't think the two are connected as the heater matrix pipes are on the passenger's side and the water in the footwell looks clear. So yes, I've got water in the car where it shouldn't be and no water in the radiator where it should be - fantastic!

Matt

[penno]

Don't want to scare you but check the neck of the swirl pot. My engine mount split on mine and the PAS pulley wore a hole in the top pipe which goes to the swirl pot. Lost lots of water. I think this can only happen with the serp engined Chims though.

Steve

[chim666]

Have a look at the joint between the front of the engine block and the timing chain cover casting (that's the best description that I can give I'm afraid). Mine went there a couple of years ago - you might see coolant escaping from the joint (it's easiest to look from the pasenger's side).
If so, it's a £12 part, but three or four hours' labour.