Series 3 - 2.25 petrol over heating

Finally got my series 3 put back together and on the road yesterday so decided to take her for a spin this afternoon to blow the cobwebs off her. While shes been stood shes been started on a regular basis and never over heated, the needle used to sit on the halfway mark at all times,After about a mile today I could see the needle creeping up and the faster I went the quicker it rose. Turned her off for a while and managed to get her back home after she had cooled down a bit. Theres no noticeable coolant loss or oil in with the coolant. Just ordered a new thermostat today and gonna replace that and hope and pray that rectifies the problem. Just wondered your thoughts,and to see if im barking up the wrong tree.Is there anything else I can check in the mean time. More than sure its not a faulty gauge or sender as the raditor is very hot as indicated although not pressurised.


Thanks in advance.

bowers1986 said:

Finally got my series 3 put back together and on the road yesterday so decided to take her for a spin this afternoon to blow the cobwebs off her. While shes been stood shes been started on a regular basis and never over heated, the needle used to sit on the halfway mark at all times,After about a mile today I could see the needle creeping up and the faster I went the quicker it rose. Turned her off for a while and managed to get her back home after she had cooled down a bit. Theres no noticeable coolant loss or oil in with the coolant. Just ordered a new thermostat today and gonna replace that and hope and pray that rectifies the problem. Just wondered your thoughts,and to see if im barking up the wrong tree.Is there anything else I can check in the mean time. More than sure its not a faulty gauge or sender as the raditor is very hot as indicated although not pressurised.


Thanks in advance.

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Put the thermostat in a pan of water and see if it opens before the water boils. Use a thermometer if you've got one to find out what temperature it opens at. Could the radiator be blocked with mud by any chance?

i'd drain and flush the cooling system if its been sitting a while, as well as checking the thermostat as fenby says.

in fact last time that happened to me the fan belt had fallen off!

Thanks for the advice lads,, removed the thermostat and slowly increased the temp in a pan of water with the the thermostat suspended from a price of string, nothing happend after 3 goes. So fitted everything back together minus thermostat on landrover and left to tick over for a while.. seems to run fine with no over heating. So just gotta wait for the new thermostat to arrive,,think I'll take your advice "Doobie" and also flush the full system prior to fitting. Thanks for your help

Just an update:

New thermostat fitted and still over heats, although no visible coolant loss.

With the new thermostat fitted (which I tested prior to fitting in a pan of water and it does appear to open slightly) it only takes a few minutes on idle to boil. Although with no thermostat fitted it will sit happily for 15-25+ minutes without over heating and slightly creeps up just passed the middle of gauge but doesnt over heat/boil and doesnt go into red on the guage.

Ive flushed the full system out prior to fitting new thermostat.

Im assuming head gasket and gonna have a go at tackling it myself, but just wondering if theres anything else I can check? When taking the radiator cap off when cold,coolant level doesnt seem to be dropping.

Your thoughts please.

Well thats a bugger innit.
If the stats the same temp and in the right way round and it still overheats it does suggest summat else.
Maybe you have a problem with the cooling system rather than the gasket.

For a head gasket check, first pull the dipstick, if you have mayonaisse then its gone, another is feel the top hose with motor running, if its rock hard then its gone, run the engine with the rad cap off (do this with a cold engine you might be squirted with hot water) if you see loads of bubbles then thats also a sign, another check is to hold a bit of glass or cold steel close to the exhaust with the engine warm, if you get more than a couple of drips of moisture condensating then thats also a sign, if you have a compression tester that sometimes can show up problems allthough can be misleading on an old motor.

Other causes of overheating could be caused by the fuel/air mixture being to weak, could check plugs for colour, if white, to weak, looking for pinky colour for correct mix, black/sooty, to much petrol. Ignition timing incorrect. But did you state earlier that all was well without the thrmostat? If so do you have the correct stat fitted, I believe there are two settings of thermostat.

Regards.

dr pepper said:

Well thats a bugger innit.
If the stats the same temp and in the right way round and it still overheats it does suggest summat else.
Maybe you have a problem with the cooling system rather than the gasket.

For a head gasket check, first pull the dipstick, if you have mayonaisse then its gone, another is feel the top hose with motor running, if its rock hard then its gone, run the engine with the rad cap off (do this with a cold engine you might be squirted with hot water) if you see loads of bubbles then thats also a sign, another check is to hold a bit of glass or cold steel close to the exhaust with the engine warm, if you get more than a couple of drips of moisture condensating then thats also a sign, if you have a compression tester that sometimes can show up problems allthough can be misleading on an old motor.

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Checked oil and all seemd fine,,,no mayonaisse effect.Top hose didnt feel all that hard really either.Did worry at first that Id fitted thermostat upside down so took it all off,,,but found it can only be fitted one way or wont bolt back up tight.

BrianW said:

Other causes of overheating could be caused by the fuel/air mixture being to weak, could check plugs for colour, if white, to weak, looking for pinky colour for correct mix, black/sooty, to much petrol. Ignition timing incorrect. But did you state earlier that all was well without the thermostat? If so do you have the correct stat fitted, I believe there are two settings of thermostat.

Regards.

Click to expand...

Replaced thermostat with the same one (74 degree), fiddled about with the mixture to no avail. It was running perfectly fine prior to this happening so more than sure thats not the cause. It will sit on idle without thermostat fitted for some time,without over heating.It does slowly creep up but not much passed middle of gauge. With thermostat fitted it seems to boil within 5 minutes sitting on idle.:doh:

Well at least that proves you have nothing drastically wrong - the very fact that it seems to be fine when the thermostat is out (i.e letting the water can circulate as much as it likes). In my mind that proves it can't be a blockage or the rad, running lean, dodgy water pump etc as that would not be cured by taking the thermostat out. Someone correct me if I am wrong!

I would check that the new thermostat actually works and is not staying closed all the time. I can't think of a way you could physically fit a thermostat incorrectly without it being obvious! Or perhaps the thermostat housing is damaged/worn and the thermostat cannot open correctly once in the housing? The housings are cheap enough to buy.

I had a similar problem with a Rover SD1 I once had. Turned out my 'new' thermostat was faulty.. so bought another and it all worked.

These days.. I will always buy 2 thermostats at the same time.. because they are cheap.. and swapping them over pretty much proves or eliminates it as the culprit. Some brands are better than others... Does $hitpart Britpart make thermostats ?

I agree with ginger puss on that one, it does sound like a dodgy stat again.
If you go and get a new stat, then it might be a good idea to get a water pump gasket and remove the pump and have a good look at it if the new stat doesnt work.
Its mentioned on one of the other threads on here at the mo that pump vanes can be lost if the block has froze, I have seen on other engines missing pump vanes through frost or lack of antifreze on some rover engines, eats the ally blades, ford even released a mod kit for their duratec, a pump with plastic blades.

Just to update this topic,,

Changed head gasket and since then had alot of problems getting her to run at all,,,and when she did it was very rough.(most of you will have seen my other topics on here)

Anyway did timing using a strobe, valve clearances upgraded to an electronic distributor and coil, re-gapped spark plugs and now she runs as sweet as ever. Although got 2 problems:

Will tick over 100% ,best ever to be honest but upon pressing accelerator,engine first sounds like its gonna stall and then revs up as it should.

and the second one been the more frustrating , she starts to creep back up to the red on the temp gauge (over heating) so basically back to square one

Took water pump off and inspected as previously said and all fine.Thermostat was new, as I changed prior to changing head gasket. Fan belt tight so not slipping. And although over heating there's no steam coming from radiator cap like before and the system isn't as pressurized, even when hot you can remove the cap with a cloth and water wont spew out like before.Theres also no visible smoke/steam from exhaust of any colour.

Any suggestions more than welcome:doh:

This suggests the water is not circulating unless the thermostat is open.
It should flow around a "by-pass" pipe when the stat is closed, and in the process heat up the bottom of the stat. Sometimes this doesn't work.

A good trick to solve this problem is to drill two maybe three (no more!) quarter inch holes through the rim of the thermostat. This will let a small amount of water flow PAST THE THERMOSTAT BULB and as the heat reaches the stat's limit, it will open up.

In winter this also has the advantage of a little warm water flowing through the radiator which helps to stop blast-freezing and carburettor icing.

It was a standard mod in all our Minis for many years.

CharlesY

Thanks again CharlesY will look into this tommorrow.

Im thinking now your temp gauge sender is faulty....test this with a thermometer in the radiator header tank...it could well be lying to you, and not overheating at all!.

As for the hesitant revving, what carb have you got and whats it tuned up like?

Jackual_NZ said:

Im thinking now your temp gauge sender is faulty....test this with a thermometer in the radiator header tank...it could well be lying to you, and not overheating at all!.

As for the hesitant revving, what carb have you got and whats it tuned up like?

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I haven't tested with a thermometer mate,, but just by touch the radiator gets hellish hot. The carb is a 34ICH Webber, I seem to have cured that problem mind,,as I took top off carb and just give everything a good clean.

You said that, after replacing the head gasket and a few other changes, it was running as sweet as ever, so if it were a faulty temperature gauge sending unit, then the readings should not have been affected. Did the temps improve after the gasket was changed...and then degrade over a period of time following? Did I understand that correctly?

If you don't mind me asking, when you said, "I just got my series 3 back together again"...what did you mean by that? In other words, was the cooling system components disconnected for some period of time? Hoses off, radiator cap off, etc?

IHMS said:

You said that, after replacing the head gasket and a few other changes, it was running as sweet as ever, so if it were a faulty temperature gauge sending unit, then the readings should not have been affected. Did the temps improve after the gasket was changed...and then degrade over a period of time following? Did I understand that correctly?

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Had alot of troubles getting it up and running again,, eventually got there in the end and swapped the old distributor for an electronic one,with sports coil,re-gapped plugs, did valve clearances and she now runs as sweet as ever, although still over heats. The over heating just happed straight away upon letting her run for the first 5 minutes, there was no gradual build up to over heating after head gasket had been done.

IHMS said:

If you don't mind me asking, when you said, "I just got my series 3 back together again"...what did you mean by that? In other words, was the cooling system components disconnected for some period of time? Hoses off, radiator cap off, etc?

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Yes the raditor and cooling hoses were removed after doing head gasket change as I removed the water pump just to check all was well there, and every thing appeared to be fine, the radiator and hoses were off the vehicle for no longer than 2 days.

I wish we could get a themal image of the radiator and motor while it is hot. The physics of this is very simple...transfering the engine block heat to the radiator is not happening. The reason I asked about the length of time the hoses and radiator components were off was due to an experience a friend of mine had with mice. They set up shop to the left and right of the fill hole in the top of the radiator...visually everything looked clear...but it wasnt. We put flake drano in the system and flushed it PROPERLY...in 5 min. the temp dropped nearly 100 degrees. The only thing I can suggest short of a real flush, is running the fluids backwards through the system and see what flows by the fill hole in the top of the radiator or into a piece of cheese cloth. It will require a sump pump and some hose and run it backwards through the block and see if you can purge the radiator vanes...the higher the pressure the better. Also, I once helped a friend who put back his water pump without installing the backer plate...it is a secondary element that forced the water to flow into the impellers on the pump...the net result without it was that the impellers just spun and spun and moved ZERO water. Is it possible the impeller has come loose from the drive shaft or is there a backer plate for you water pump?? If the pump is moving the water, then the water is not moving! Find the blockage. See if you can rent one of those snake cams from the local tool rental place and look inside your radiator and other block orifices. You will find it!