Help please: Overheating and coolant leak?

[richlaz]

Just brought my van back from MOT (all passed surprisingly apart from small bit of brake pipe corrosion!)...

I noticed the temp gauge was around three quarters of the way up (1.9 DG engine). Didn't really think too much of it, as it's quite hot weather, was start/stop traffic for quite a while, and I was almost home anyway).

When I got home and parked up (parked on hill facing downwards), got out of the van and noticed a load of coolant pee'd out from somewhere at the back of the van. Looking down the street, no trails of fluids, only happened when the van stopped?

I'm not very good mechanically - so not too sure what it could be. Opened up engine lid, which was quite a bit hotter than expected. Can't see where the coolant could have been coming from. The coolant filler tank is around half way between the min/max markings, and the tank to the left looks almost full (Can't open lid because of the pipe attached to it - and it's still red hot).

Any ideas what the problem could be? Is there some way of visually checking if the water pump is working (everything looks/sounds fine and belt turning ok).

Also, is there some sort of overflow outlet somewhere where this could have came from? I have no clue how this cooling system works.


Many thanks in advance for any help - really stumped

[kevtherev]

Did you hear the radiator fan running at any time?

[300CE]

Also check the small hoses at the back that connect to the bleed rail to see if any have split.

[richlaz]

Cheers guys

I didn't hear the fan coming on at any time...

The radiator was definitely warm. I think there's a temp switch on the radiator for the fan?

Will go have a proper look around the engine bay now it's cooled down a bit - see if I can spot something

[kevtherev]

Cheers guys

I didn't hear the fan coming on at any time...

might be your problem then, test the switch (wiki)

[richlaz]

Just had a good look around engine bay - can't work out where it's coming from - possibly overflowing from the top of the expansion tank...?


Cheers Kev, just found the section of the Wiki - will pop off the lower grill and have a play (coming to think of it... I don't think I've ever heard the fan working - so could well be the switch - or the fan itself!)

[CovKid]

Pop the fan belt off and try wriggling the water pump pulley. You may discover there is play in it and the pump has failed. They usually eject water when they go and its more noticeable once the belt is off.

http://www.youtube.com/watch?v=LghNy400HzI" onclick="window.open(this.href);return false;

If thats the case, welcome to Covkid's thermostat bolt nightmare......

https://club8090.co.uk/forum/viewtopic.php?f=37&t=130628" onclick="window.open(this.href);return false;

[richlaz]

Just been out to have a play. The wiring colours of my of my temperature switch isn't exactly as described on the Wiki...

The centre wire (red/black), when connected to one of the outer wires (red/white), the fan comes on (not sure if this is high or low speed... seems fast ).

But... when the centre wire (red/black) is connected to the other outer wire (red/blue) - nothing happens.

With this shorting strap still in place (the non-working side), I removed the fuse box and re-seated all of the earthing crowns (a couple slightly corroded, but gave them a good scrape and wiggle but fan didn't kick in). Will have to get the crimping set out tomorrow and re-terminate the corroded connections, then try the fan test again to eliminate any possible earthing problems.

Also, I dropped the spare wheel out, and re-seated the big 3-pin plug to the actual fan motor (with shorting strap still in place) - but no joy.

Is there any way of testing the motor properly by applying voltage directly to it? How exactly does the two speed work... is 12v applied to one or other of the inputs, and the speed managed internally by the motor? (there was two coloured wires, and one brown, which I'm assuming is the earth).



So it looks as if there may be (at least) two faults... the fan works on one side of the connector when shorted out, but didn't work today when temp gauge was three quarters to the right (which sounds as if the switch may be faulty)..... and it looks as if there may be a fault stopping the other fan speed working, either a wiring problem or the motor itself...?


Cheers CovKid... will drop the belt off and have a look (then struggle to get the belt back on lol )

[richlaz]

Just loosened the alternator and slid it down the slot to remove tension, and checked the water pump pulley... there is a little bit of play, and a "clunk"... so that's another problem to add to the list...

Almost ready to scrap this bloody van... just need one more thing to go wrong... do I laugh or cry...

Looking at the radiator fan wiring in the Bentley manual (Page 97.59)... the one part of the switch when closed directly operates the fan, but there appears to be a radiator fan relay for the second part of the switch, so that's another thing to check, if I can work out which relay it is

[CovKid]

If the pump goes (or has gone) it expels water in the engine bay, the level in the rad can drop, forming an airlock and the radiator thermoswitch may not sense boiling water = overheat. I wouldn't give up just yet but you do need to suss out where the water loss is. You could try getting engine up to temp, revving it to aroubnd 2,000 revs and bleeding the rad, thats the first port of call.

If the pump is now leaking you'll need to replace it and if its a DG, I've documented this:

https://club8090.co.uk/wiki/Co ... overhaul_3" onclick="window.open(this.href);return false;

I was where you are just last month but I did get through it.

[The Bishop]

I suppose it is worth filling it up with water and see if any gushes out. That would give you are starting place.

[richlaz]

Sounds like a good plan - will try and work out the wiring problem first - as the fan should work on both speeds when shorted out, so that needs looking at anyway... then once I know the fan definitely works... will top up the water... get engine up to temperature, and see how what happens

Looks a good write-up on the water pump CovKid - If I do have to change mine - I can see me having a similar nightmare with the bolts

Looking at where the van was parked facing down the hill, and where the water stains are on the ground... I'm pretty sure the coolant was coming out further back than the pump (I.e. expansion tank area)... although that doesn't mean the pump isn't buggered anyway

[ghost123uk]

Also, is there some sort of overflow outlet somewhere where this could have came from?

Yes, sort of, read on...

I have no clue how this cooling system works.

OK, just to help you understand it. The white tank behind the number plate (the expansion, filler or top up tank, call it what you will) is not sealed. When the van is cold it is supposed to be about half full (between the two marks).

When the engine is up to running temp, the coolant expands and some of it gets pushed out of the other tank (the one on the left, which is supposed to be full to the brim) and goes into the expansion tank.

As the engine cools down the main coolant volume shrinks and in doing so "sucks" the extra bit back from the expansion tank (via that thin pipe). Now, if your engine had overheated it is quite possible that the tank behind the number plate had got overfull and leaked coolant out via its breather hole (near the top).

Note, for the above to work properly, especially the "sucking back" bit, the cap and pipe need to be in good nick and airtight, or it just sucks air into the left hand tank, leaving the expansion tank over full.

~~~~~~~~~~~~~~~~~~~~~~~~~

On the other hand, those left hand side tanks (header tank) have been known to fail. They can leak from where the low coolant sensor fits, at the very top, or they can develop a split that sometimes only opens under pressure The ones that JK and GSF sell are well known for both faults. The ones Brickwerks sell are fine however (sorry Ralph )

It does sound like (as Kev suggests ^^^) a non working rad fan/switch/relay might have triggered all this off.

[ghost123uk]

Additional = Just thought, if it had leaked from the expansion tank, behind the number plate flap, normally one would expect quite a lot of steam to be seen, as it would drop coolant onto the hot silencer.

[richlaz]

There was a lot of "hissing" as it was coming out...

I did a bit of investigating today - I believe the information about wiring positions in the Wiki is incorrect?

https://club8090.co.uk/wiki/Co ... diator_fan" onclick="window.open(this.href);return false;

The red/white is indeed the supply, which had 12v on it... but that wire isn't in the middle of the plug as stated in the wiki, it's on the end. That's why the high speed fan wouldn't work last night (because I was shorting the two outputs).

When I shorted one end (red/white) to middle (red/black), the fan came on low speed... then when I shorted both ends (supply - red/white), with opposite end (red/blue), the fan came on high speed - so fan all tested ok - suspect rad temp switch faulty

Although then the fuse blew - some previous owner numpty replaced the 16A fuse with an 8A (and wired the radio into the same fuse... What the blithering heck?)... which obviously isn't enough current for the fan at high speed

I also removed the earth crowns... wire brushed and emery clothed them to clean them up, and then fitted new crimp terminals onto the corroded plugs

I put a bit more tension on the belt in engine bay, as it felt a bit slack. Due to the water pump pulley being a bit wobbly... it now makes a bit of a noise... so water pump/thermostat next on the list, and obviously refresh the coolant Not looking forward to taking off the water pump after hearing some horror stories about seized bolts... might start spraying them with plusgas