Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Sir Tigger KC]

I've driven from Dorset to South Wales this afternoon, with the AC set at 18, outside temp 26-7 and engine temp somewhere between 95 -100 degrees.

All good until I hit traffic, slowed down and I saw the engine temp was 105 degrees and climbing!    So I turned the AC off and ran the heating on high for a bit which brought the temp back down.  This happened a couple of times later as well. 

The temp is fine with the AC on at cruising speed and fine with the AC off round town.  It seems to climb towards the red when I've been at motorway speeds with the AC on and then have to slow for traffic or coming off at a junction. 

The coolant has recently been flushed and renewed and I flushed the matrix as well. The AC has been regassed and pressed into action for the first time in years! 

 Any thoughts chaps?    TIA! 

[Andy H]

Do all three fans work? Does the single big one on the engine side of the radiator kick in when the engine is up at 100 degrees or more?

There should be a guide to testing the radiator fan operation but I can't see it at the moment.

If a switch in the radiator is faulty (there are two) then this might help Replacing a fan switch.

[Andy H]

Found it 

[omega3000]

Partially blocked core on the engine rad  Any water leaks ?

[Sir Tigger KC]

Andy, thanks for the info but all three fans are working. 

Emd. Water leaks, here's the thing!

I did have a leak but only when the AC was on, so I replaced the HBV with a 2nd hand one that had no signs of leakage and then it always leaked!    Today though it looks as though it hasn't leaked, whereas usually on a trip like today I'd expect to lose about an inch from the header tank. 

I'm wondering if the HBV is stuck or blocked or something!    The things are crap and the one that I recently pulled out was practically new! 

[omega3000]

Mine old elite held watertight sometimes then when hot days stuck in traffic it would rise into the red zone and boil over , not sure about the significance of the a/c on an off on yours
Mine was partially blocked engine rad + one of the sensors was dripping on the side of the rad losing water ... check the drain screw not weeping or pressure test system ..

[Sir Tigger KC]

When it does leak it's from the HBV and/or associated plumbing as it leaks down the back and the coolant bridge and oil cooler plate seem OK. 

[Andy H]

The fans are all working and the problem manifests itself in high ambient temperatures when the engine is under load.

Time for a new radiator IME (unless you can successfully flush the old one).

[chrisgixer]

Is the water system holding pressure? Cap tight and valve working, no cracks round the bottle neck? Water level correct? Has it bled down since the coolant change? Tried burping the pipes in case there's an air lock.

Can you get an infra red thermostat on the rad and check for cold spots before condemning it.

If the ac comes on and off as required then that implies the vac to hbv is working. If it leaks in an ac mode, and not in another, and the hbv change has not affected that then that implies there is a leak in one of the plumbing inlets to the hbv from coolant bridge etc...

Scuttle off and engine running, play with ac settings while inspecting the plumbing for leaks. IMO.

[Sir Tigger KC]

Yep the system holds pressure, it has a new expansion tank and the cap fits! 

The coolant change was a couple of months ago when I replumbed my LPG vapouriser and I'm sure that the system was bled/burped OK  and there are no airlocks, but will give the pipes a burp just in case! 

When I had it all stripped down I pressure tested it and worked the HBV but couldn't spot any leaks.   

I've been thinking about this today though, and when I flushed the system I attached the hose to the pipe on the coolant bridge and flushed it that way.  Loads of crap came out, but I remember thinking that I should have disconnected the big rad hoses as I've probably flushed loads of crap out of the oil cooler chamber and waterways into the rad....   

[Andy H]

Yep the system holds pressure, it has a new expansion tank and the cap fits! 

The coolant change was a couple of months ago when I replumbed my LPG vapouriser and I'm sure that the system was bled/burped OK  and there are no airlocks, but will give the pipes a burp just in case! 

When I had it all stripped down I pressure tested it and worked the HBV but couldn't spot any leaks.   

I've been thinking about this today though, and when I flushed the system I attached the hose to the pipe on the coolant bridge and flushed it that way.  Loads of crap came out, but I remember thinking that I should have disconnected the big rad hoses as I've probably flushed loads of crap out of the oil cooler chamber and waterways into the rad....   

I think you may be right.
If you have the time and inclination you may be able to flush it out of the radiator again