Overheating problems

[MarkH]

It seems that 8 months off the road while rebuilding my 1800E hasn't done it much good...

I took it for it's MOT and it passed first time! Great, couldn't wait to pick it up...on the 10 mile drive home about 500 yards from home the water temp crept into the red and coolant starting dripping on to my feet.

Not being amazingly mechanical I've so far replaced the Thermostat, checked all the hoses and throughly flushed the system, replacing the coolant in the process.

The car still overheats and I'm not sure what to check next. Any help gratefully received.

Thanks

Mark

[740Estate]

Check the water pump and also made sure the radiator matrix isnt blocked?

[stuart131]

Hi & sorry to hear youve brewed up, had the same thing with my Amazon last year, firstly the heater valve had corroded (where the 2 heater pipes join above your left knee) and coolant dripped onto my leg/floor etc.) Not only this, but as suggested by a kind soul on this forum, I also had an airlock in the pressurised system. cured by taking top off the overflow bottle and revving until cleared. Im told that you can also undo the temp guage nut and release the pressure that way - but never tried so be careful.

I hope you get it sorted

best regards

Stuart

[MarkH]

Thanks for the replies so far,

I'm pretty sure it's not the water pump as that failed and was replaced 18 months ago...I will try the airlock fix, but would completely emptying and refilling the system not have prevented this?

Also, having just come in from the garage, when the car was just about to overheat there was a faint hissing sound coming from a round black object between two pipes (picture attached) - Could this have any bearing on the problem?

Thanks

Mark

[Andrew (UK)]

That object is not original to the car. I guess it is a valve to shut off the heater flow which suggests that the normal heater valve had failed some time ago. The coolant dripping on your feet also suggests that the heater valve is now leaking as well. So first thing to do is replace the heater valve. It is quite hard to fill the coolant system without leaving air in it as some parts in the heater circuit are higher than the top of the radiator. Also make sure you have the correct thermostat with the bit that seals off the pipe in the head. When refilling with coolant and first running the engine, make sure the heater valve is open so that air bubbles get flushed out instead of just expanding where they are and pushing all the coolant out of the expansion bottle.
See this thread for pictures of right and wrong stats.
http://www.volvoforums.org.uk/showthread.php?t=21639

Andrew

[Derek UK]

I think that's the non-return valve in the vacuum pipe to the servo so probably not relevant to your problem. Shouldn't hiss though. Remove and clean. If "oily" it could be hydraulic fluid that's leaked through from the brake master cylinder. If it shows white smoke from the exhaust when coming back on the throttle after, say, going down hill off throttle you might need to look at renewing the seals.
Areas to check as previously mentioned in earlier posts. Correct thermostat, correct rad caps which seal properly, fill and bleed with heater valve fully open. If it's leaking, could be the heater matrix, you'll want to fix it by winter if it's a daily driver. Remove rad and back flush. Trying some "Radflush" won't do any harm but doesn't usually clear really bad blockages. Helps to loosen things up before back flushing.
Keep us informed.................
Derek

[mike gilbert]

The 1800E often came with a viscous coupling on the fan. If yours has this type of fan make sure the coupling is working (the fan will spin freely when the engine is cold but the coupling locks it in place when hot) if you can spin the fan by hand when the engine has got very hot or overheated, then the coupling has failed.
Mike.

[MarkH]

Thanks to everyone for the replies,

The viscous fan coupling seems to be ok, and I traced the original leak (over my feet while driving) to the heater control valve.

I removed the valve, the 2 hoses that go to the heater box and the heater box itself. I then removed the heater matrix, checked it for leaks and gave it a good flush through with clean water. I then replaced the matrix, fitted the new heater valve and replaced the two hoses that come out of the heater control valve.

I refilled the radiator and topped it up twice but still no joy! The car still overheats!

[Andrew (UK)]

When you say it overheats, what happens? Do you get a high reading on the gauge or something else?

Andrew

[MarkH]

Thanks for the reply,

The first time, I was driving back from the MOT centre and the needle creeped upwards into the red area and reached the top. After a little while at the top the heater valve gave way.

Now when I run the engine the water temp gauge creeps up, pauses at normal temperature and then proceeds all the way to the far right of the red area. The expansion tank goes to almost full, and there is a lot of heat coming from the engine bay. I can't find any loss of water from anywhere at all.

Thanks

Mark