Lots of steam
 

Just when you think that my troubles with are Banana are over, then she throws up a new problem.

Back in February I had a new radiator fitted, and I put on a new radiator cap, bought from DMGRS.

Yesterday we had lots of steam coming out of the overflow pipe. When removing the radiator cap there appeared to be no pressure noise. I keep the coolant at the correct level. No oil in the water or water in the oil. Oil cap is clean and the dipstick is showing the correct level.

Started with the onboard diagnostic check and temperature was showing 92 degrees. So we carried on with our trip. The temperature needle stay at the quarter to nine position and I ran with the diagnostic check showing on the dash. On the downhill sections the temperature dropped to 81 and on the uphill bits it went up to 90.

Done a round trip of 80 miles and she pulled like a train. Got home to be greeted by more steam coming out of the overflow pipe.
Been out this morning and no coolant to be seen. I have put about half a pint in.

Could it be the Pressure Relief Thermostat that is playing up? It was last replaced about 8 years ago.

Hi Bob,

The initial possible diagnosis is that your cooling system isn't pressurising properly. Remove the DMGRS expansion tank cap and re-fit the original. Repeat a journey involving uphill and downhill sections. Is there an improvement?

Simon

No more steam
 

Many thanks Simon.

Changed the cap, took her for a good run. Never once went over 88 degrees and even dropped to 79 on a downhill section.

Well that's ruled out the cap then! :D

It appears that you have a defective seal somewhere in the system. It will be tricky finding it but start with the basics:

• Hose clamps
• Is the bleeding screw loose? (Don't go mad and overtighten it.)
• What about the plastic elbow at the top corner of the radiator; doesn't that sometimes crack?

Simon

No, stayed exactly where it should have been.

I think you've solved the coolant loss then.

Your temps are now right where I'd expect them if the PRT is a DMGRS aftermarket 82C example.

Hi Bob,

I'm sorry to have to say this but I don't agree with what Michael (mbonwick) has said here. Your coolant temperature should never drop as low as 79˚. The thermostat is designed to keep it at a minimum of about 92˚. When the car is stationary or slow moving in traffic, this should steadily increase to 104˚ when the slow speed fan should trigger.

Your temperature is varying widely depending upon engine load which is not correct. Your system is not pressurising which means that you won't have the protection of a raised boiling point. When the conditions are right you will continue to lose coolant, but it will be intermittent. Having a 1.8 you're then at risk of the incorrect diagnosis of head gasket failure. :o

I had exactly your symptoms with my SD1 many years ago. The expansion tank was metal and the outlet pipe was brazed into it, except it wasn't! When I tried to remove the hose clip, the pipe wobbled. There was no coolant loss from the site, it was being ejected through the cap overflow but intermittently. Once that connection was repaired the fault was cured.

There's nothing for it Bob but a painstaking investigation I'm afraid. It's amazing what you can find when you really look! ;)

All the best,

Simon

Hi Bob hope you are well, if you had steam from the old cap and have changed the cap and now dont have any steam or coolant loss sounds like it is sorted

Also if you the 82oC thermostat those are about the running temperatures I would expect

Dave

I’m not mechanical minded, and I have to leave any investigation to those who know what to look for. However I have ordered a new PRT and will get that fitted.
I cannot see any leaks with the engine running, even shining a torch into the hidden depts of engine bay.

But all your suggestions, and those of others have been taken on board.

Many thanks.