question overheating 101

[MiketheBike]

Just taken delivery of the 101, but slight problemette.

 

Motorway driving fine, steady (30+mph) driving fine.

Anything below that in it overheats badly (off the scale badly). Cools down quick enough, and when up to speed again it stays in the correct temp range.

 

My first thought is the fluid coupling on the fan, would that be a good first check? How do I check it, and can I temporarily lock out the coupling to prove it before buying a new coupling?

 

Cheers

 

Mick

[Poptopshed]

When the engine is hot the fan should be stiff to turn by hand and when cold it should spin freely. Its a simple check to see if the viscous unit on the fan is working.

[MiketheBike]

I did try that but lost three fingers...only kidding

so just get it up to temp, turn the engine off and try to turn the fan by hand?

 

Cheers

 

Mick

[antarmike]

I did try that but lost three fingers...only kidding

so just get it up to temp, turn the engine off and try to turn the fan by hand?

 

Cheers

 

Mick

 

well try it by hand with the engine cold first, so you have a comparison....then warm it up....

[Dakar]

Probable cause is partially clogged radiator.

They've frequently been run with no antifreeze and corrosion has occured within the engine.

Aluminium sulphate is a white powder which clogs the rad.

Try a good reverse flush.

[MiketheBike]

cool, thanks guys I will check out the fan first. I may just give it a flush anyway so I know where I am before winter really sets in.

 

Mick

[sean101ryan]

Your're getting the reverse of the normal overheating problem which probably rules out the radiator. Could be the viscous fan not working at idle but a possibility is the vanes badly worn in the water pump, shifts water when revved but not shifting enough at idle.

[R Cubed]

So if it overheats when stationary try revving it to 2000 rpm ish to see if its an engine thing or weather it has to have the air speed rushing through the rad to cool it, also check the fins between the rad tubes these can some times fall out, become detached from the sides of the tubes, and they DO make a big difference to the performance of the rad.

[Tony B]

Check the oil cooler system as well. Oil cools the engine as well. Very obvious, what state is the fan belt in? Also knowing 101 electrics, try the sender and gauge. Most engine tempratures will rise after the engine has been run hard and then idles.

[rbrtcrowther]

It does sound like the viscous coupling has packed up. With the engine cold and revving at about 1000 rpm the fan should sort of free wheel and as the water warms up the air the fan is gently pulling through the radiator will warm up the fan bi metal strip moving a little valve in the hub and the fan will lock up and turn the same speed as the water pump pully. Have a feel of the bottom hose too if it is the same temp as the top hose there is not enough air cooling the rad if it's cold the water ain't circulating. most viscous units will be stiff to turn before the engine is started cos the fluid will have pooled in the bottom of the unit. when the engine is started and reved the fan will roar for a moment as the fluid is spun out with centrifugal force and then it will go into freewheel. hope this helps god luck and mind your fingers:D

[sean101ryan]

"try the sender and gauge"

 

They are both capillary units on a 101 if original, no electrics involved and are more accurate. Oil cooler won't have much of an effect on the temp overall unless very hot.

[MiketheBike]

I have not had much of a chance to check it out as I have put my back out, so cannot even get in to drive it

How much force should there be from teh fan with the engine at working temp? I have looked in the small hatch where the oil filler is and its not a gail.

Hopefully if my back plays ball I will have a look at all those points at the weekend. Thanks guys

 

Mick

Edited November 25, 2010 by MiketheBike
added comments

[sean101ryan]

Hope your back is sorted, 101s and bad backs don't go together.

[MiketheBike]

After all that I think it was just the radiator cap. At normal running temp its hissing, so the run back after purchasing I just think it lost a lot of water....what a numpty. It may be that the cap is knackered or its the incorrect cap. I see that craddocks have them, so at £1 each I may as well buy a couple

[griff66]

easy stuff first!

[protruck]

once you have the new cap it may still be worth flushing the rad out.

 

 

 

Clive

[MiketheBike]

Clive,

 

I think you are right, certainly cannot do any harm.

WOuld you suggest just running it through with a hose, or using rad-flush?

[Tony B]

If you can get Forte stuff. You can get it through Amazon. Not cheap but they do a full range from flushers to stop leack, and it is good stuff.

[protruck]

Id just run it through with the hose pipe to start off with and see how much crap comes out.

 

If there seems alot then maybe use some rad flush in it.

 

When you file 50/50 mix with Antifreeze & water get some Demin water for your local

car parts supplier and mix that with the antifreeze instead of using normal tap water.

 

Hope this is of help

 

Clive

[rbrtcrowther]

Er......don't want to worry you but a continuous hissing from the radiator cap could mean combustion gasses being blown into the water jacket:cry: Are the hoses rock hard too? It could just be the rad cap but it would lose water and boil over at a lower temp. The Cap may have failed the waters boiled and the head gaskets packed up. The rads gone on our old crane at work so we run it with the cap loose to stop it pressureizing and blowing the water out when it warms up and cools down. There is no hissing when up to temp in fact you can remove the cap with it running. It is also a V8 ,but a cummins V8 :cool2: With no exhausts either:evil:

[MiketheBike]

Hi,

 

it only hisses when up to temp, and also when up to temp with the engine turned off (until I release the pressure).

I checked the oil and there is no gunge....you did make my heart sink though!!

I crimped the tabs down a bit on the rad cap, and its hardly doing it now (but will still get a new cap), and its lost no water after a few short runs.

 

Super

 

Mick

[Tony B]

If they were all that easy! Good point though Rad caps and distributor caps seem to be taken for granted. :-D

[griff66]

nice cooling airflow when u moving none when stationary , and the thing bout ferrets is does not matter if stationary or moving no speed related airflow thru rad!

[Tony B]

You can get one rather odd overheating problem with 101's. Umpteen birds nesting on the oil cooler!:-D

[rbrtcrowther]

Well i'm glad it was the cap:-) When i have had even the slightest overheating problems it has always been something major like the headgasket or a dropped liner:embarrassed: