Series 3 - 2.25 petrol over heating

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Update:

Removed thermostat today and drilled three 5mm holes in it as "CharlesY" suggested, back flushed whole system but not much change there really as water was clear coming out. Started her up and let her idle, she stayed low in the temp gauge for quite some time,, got strobe out and re did timing after noting it was slightly off. She was then left ticking over for about 20 minutes with the temp increasing very slowly (unlike previousley where it would boil within a few minutes). After looking at temp gauge I saw it creeping just above the "N" mark in middle and started to curse as she used to always sit bang in the middle. But left her still idling for a further 15 minutes and reving her and she doesnt go past this point so think ive solved the problem. Radiator cap can be removed now at anytime with engine running and hot and she doesnt spew water everywhere like previousley.

Is there anything in her reading slightly higher on the temp gauge than before, or is this nothing to be worried about.


Thanks for all your advice and input lads,,,, couldnt of done it without you lot:)
 
Super!

What a result 3 little 5mm holes can make! It's a patented idea by the way.

Don't worry about the temp gauge reading a little high or low. It measures only a very narrow band of temperatures, and leaps up very fast when the temp gets even just a little hotter than usual, or indeed a little lower temp makes it show a LOT lower.

The thing to observe is, on your gauge, WHAT IS THE NORMAL RUNNING TEMP?

As soon as it gets to that and stays there, all is well, but STOP and investigate quickly whenever the temp gauge goes higher than the "normal" level on your dial. Any sudden rise is a fair warning that something might be about to go wrong, and VERY hot.

The proof of the pudding will be taking her for a drive, and a long steady uphill climb.

CharlesY
 
Last edited:
CharlesY said:
Super!

What a result 3 little 5mm holes can make! It's a patented idea by the way.

Don't worry about the temp gauge reading a little high or low. It measures only a very narrow band of temperatures, and leaps up very fast when the temp gets even just a little hotter than usual, or indeed a little lowertemp makes it show a LOT lower.

The thing to observe is, or your gauge, WHAT IS THE NORMAL RUNNING TEMP?

As soon as it gets to that, all is well, but STOP and investigate quickly whenever the temp gauge goes higher than the "normal" level on your dial. Any sudden rise is a fair warning that something might be about to go wrong, and VERY hot.

The proof of the pudding will be taking her for a drive, and a long steady uphill climb.

CharlesY
Click to expand...

Cheers mate - Will take her out for a run tommorrow and post the result here tommorrow tea time- Thanks again CharlesY Much appreciated:)
 
Interesting. I may do the hole in the thermostat mod to mine too. I am running ht since I replaced the radiator with a newer style one. I think my problem is that I am not running it with an expansion tank when I am pretty sure it should. What makes me think this is that the rad cap that came with it is rated at 7PSI...whilst the workshop manual says 9/10 PSI - suggesting it is a lower PSI designed to flow into the expansion tank?
 
rustyrhinos said:
Interesting. I may do the hole in the thermostat mod to mine too. I am running ht since I replaced the radiator with a newer style one. I think my problem is that I am not running it with an expansion tank when I am pretty sure it should. What makes me think this is that the rad cap that came with it is rated at 7PSI...whilst the workshop manual says 9/10 PSI - suggesting it is a lower PSI designed to flow into the expansion tank?
Click to expand...

The PRESSURE cap does NOTHING for the flow or where the water goes. All it does in INCREASE the pressure at which the coolant BOILS. Your START point in the table below is 1 BAR, normal atmospheric pressure. Water boils at 100°C / 212°F at this pressure. If you fit a 7 pound pressure cap that adds about half a BAR pressure to the system, so the pressure is now about 21 - 22 psi absolute, and the coolant won't BOIL till it is way up about 110°C, by which time your temp gauge will be on the wrong end of the red bit I reckon. A 12 pound cap will increase the boiling point even further. We used 15 pound caps on all our competition cars way back in the good days.

CharlesY


water-pressure-boiling-temperature-2.png
 
Fair enough, thanks for that.

But as the PSI is lower on the cap that I now have, it will therefore lower the temperature boiling point and make it more likely to come out the expansion pipe at a lower temperature?
 
rustyrhinos said:
Fair enough, thanks for that.

But as the PSI is lower on the cap that I now have, it will therefore lower the temperature boiling point and make it more likely to come out the expansion pipe at a lower temperature?
Click to expand...

Yes, it will boil at a slightly lower temperature, say 108°C instead of 112°C.
That means you see clouds of steam a little sooner, and stop.

CharlesY
 
Indeed - but could a lower boiling point also hinder the cooling system though? What I mean is if the water boils at a lower point to what the engine and coolant system is designed to have, it will create bubbles too early which are not good for cooling, making a quick rise in temperature.

I still want to run with an expansion tank anyway just as a test really to see wether if it has a bit of tolerance for water boiling and overflowing if it will help. Not quite sure why I see some series vehicles fitted with them and some not.

Also not sure why my pressure cap says 7PSI when the workshop manual says 9/10PSI but there you go - and all the references caps you can buy say 9PSI. Perhaps I should go for the correct pressure cap.
 
Believe me, if the coolant is anywhere near boling point even with no pressure, the temp gauge will be right off the red end.

Don't think about flow and temperature - there is no connection whatever. If there are steam bubbles in the coolant your engine is OVERHEATING, the GAUGE IS OFF THE RED END, and you need to STOP.

CharlesY
 
The pressure cap needs to be the one for the engine , as fitting a lower pressure cap can cause probs due to flashboiling at hotspots in the engine , having an expansion tank is not relevant from a pressure cap point of view . The reason for exp tank is mainly due to type of rad i.e. crossflow rad cooling area reduced by lack of water intop of rad , as water expands on heating, if pushed out past pressure cap then cant be sucked back in when cools . so to keep rad full need reservoir (exp tank) . HTSH
 
CharlesY (or anybody),
Do you have any numbers for what red and "N" on the T gauge mean? I'm hoping that the high reading of the 109's gauge and sender in my Peugeot Turbo-diesel just means that the 81C-93C (Pug') thermostat is deliberately running hotter than the Series III gauge is expecting.
Hope you're still out there in...the LandyZone...
Steve, in the NLs
 
Hi bowers1986

Did you manage to sort your heating problem out . I have the same problem with my 2a I have done pump thermostat radiator. All new and she is doing the same thing . Head gasket all fine compression test done etc . New sender new voltage stabilizer .. Anyone with any points would be appreciated
 
I have exact same problem in 2.25 diesel series 3 after doing valve guides! I am going to stick a new engine in it as I have done all the suggested cures and it only runs well with holes drilled in thermostat or no thermostat, interestingly rad gets hot at top and pressurises hoses whilst bottom stays stone cold. You have my sympathies for this issue it is a pig to sort out.
 
Ok just let you no sorted my temp reading out after new radiator pumps thermostats the works . All it was , was faulty senders and volt stabiliter Brit parts blue box .
 
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