Jump to content

Over Heating or Not


Recommended Posts

Not sure how much of a problem this is yet. 2.25 Petrol. not on the road yet in the process of rebuild.
Dont think there is any water coming out of top hose into engine, or bottom for that matter, first thing I done was pulled the thermostat out and done the check in boiling water and it opes and closes OK.
Symptoms are Rad getting very hot top and bottom , exhaust and manifold to hot to touch.
tonight I let it run for a good 15 minuets, looked and seemed fine but could not feel ant water running through hoses. Did not loose any water at all but when I turned engine off there was steam coming from rad cap, lossened it slowly and carefully but no water gushing out.
Thinking it could be water pump is there a way to check pump ?.



Link to comment
Share on other sites

You won't feel water flowing through the hoses, it is quite slow really, even with the thermostat fully open.

Once the thermostat is open, the radiator will be around 85-90C at the top, and should be a bit cooler lower down. Exhaust and manifold will ALWAYS be too hot to touch, after just a minute or two running.

As you radiator is getting hot, I would say your pump is working, otherwise it would remain cool.

Don't ever remove the radiator cap from a hot engine, so dangerous.... no matter what you may see on YouTube, permanently scarred faces are not fun. If there is team coming from it while running it could be the cap seal is damaged, remove and inspect.

But before all that, as Fridge is suggesting rather cryptically, check the temperature gauge or use a temp gun (cheap on amazon/ebay) to see exactly what is happening -nothing on the engine except the exhaust/manifold should be over 100C.



  • Like 1
Link to comment
Share on other sites

Personally I would trim 10-15mm or so off that top hose where it connects to the thermostat housing. That would allow the 90 degree bend to be a more natural shape and allow some of that "squash" at the elbow to be eased. That will increase flow through the hose.

Series water pumps aren't very efficient and don't shift much water especially at low revs/idling. The top hose will be too hot to hold - 85-90C but the bottom should be just cool enough to touch. Mind the fan! best to check from underneath the front cross member and touch the bottom tank of the radiator.

BTW, the fan will do practically nothing useful without the cowl being fitted to the radiator. That will massively improve cooling, that should be sufficient for UK weather, but you may find you need the metal cowl section as well which fits on the battery side of the engine on days over 25C.

Edited by simonb
Link to comment
Share on other sites

I can’t agree more with Simon’s comments, especially about the fan cowl - a fan like that, especially with no wings or bonnet, will be utterly ineffective, drawings air from around the rad rather than through it.  That is what the cowl does - ensures that the fan pulls the air through the rad rather than just stirring the air behind it.  It will also save your fingers when fiddling in the engine bay. 

As Simon said, 1/2” off the front end of that top hose would help water flow and hose longevity.


Series and the 2.5l water pumps aren’t fantastic and aren’t effective at low rpm - it is not uncommon to see a labouring engine at low revs build heat fast, but shed it very quickly by dropping down a gear or two to increase engine and thus pump rpm.


The fact that you quickly get hot rad hoses suggests adequate flow, but the bottom hose should be markedly cooler than the top, so it suggests that the rad is not doing its job.  My suspicion is that the missing fan cowl is the problem, but if fitting that doesn’t result in a cooler bottom hose (think markedly less hot rather than cool), then I’d suggest the rad is blocked internally and may need a strong flush or a recore.

Link to comment
Share on other sites

For ongoing peace of mind, temperature indicator labels are your friend:


Available from many suppliers like RS / Farnell  / CPC plus (more expensively) from motorsports suppliers. I stick them on anything of interest and replace each service - top of the rad, oil flter, sump, gearbox, transfer box, overdrive...

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy