Overheating mysteries

[savetheminis]

Hi everyone, I am having an overheating problem that seems to be baffling the mechanic.
It is a wolseley 1300 engine that hasn't seen much use since it was rebuilt (maybe 200km, in storage for about 4 years).

Symptoms
- overheats at idle if started from cold, in about 10-20 min.
- cools down when driving, starts to heat up again if stuck in traffic. revving high/using low gear helps.
- on the motorway, it will usually hover around 3/4, running the heater brings it down a bit. on downhills the gauge sometimes reads below normal.

Steps taken so far
- flush radiator (was full of some slimy stuff - product of two incompatible antifreezes?)
- replace thermostat
- check gauge is correct
- check hoses
- check water pump impeller gap (it is a new pump with a pressed steel impeller)
- leakdown test (ok)
- check timing (was overly retarded due to wrong timing marks) & carbs (running fine)
- check heater (works fine)
- check radiator is working, with thermometer
- check fan/water pump pullies (they are the smaller ones)
- fan is a plastic one

The engine runs well apart from the overheating problem. Oil pressure is about 65psi.

Only think I can think of is a blocked water passage between head and block?

Also, if anyone in the Christchurch/Otago NZ area has a good used front bumper with overrider holes, mine got pranged in the earthquake. Also after a new or rebuilt upper right door hinge.

[999 ORX]

just a quick thought, is the fan on the correct way round?

[savetheminis]

I've been told it is, but I'm going to double check with them.

[mk1]

Sounds like the fan on the wrong way round to me too.

[mk1rally]

yes, Fan. If it is the right way, have you tried running with a 6 blade export one?

Also, have you had the water pump off to check its the right one and the impellor is not loose?

[savetheminis]

The impeller has 25 thou clearance apparently. Not sure what is the right type for the engine (approx '68 wolseley 1300) apart from that it has a bypass connection. I'll get them to check the fan again tomorrow.

On the subject of water pumps, are old ones (circa mid 1960s) reusable if they are in good condition?

Thanks everyone

[Vegard]

Would the fan reallt make that much of a difference? It still blows the same way.

The solution is this: Fit an Allegro radiator with the electrical fan. Do it!

[999 ORX]

Would the fan reallt make that much of a difference? It still blows the same way.

The solution is this: Fit an Allegro radiator with the electrical fan. Do it!

Does it? I thought it draws in air the opposite way!? Otherwise what would be the point in having a front and back? Either way its less efficient the wrong way round, this is probably why when driving it cools and when stud still it gets hot. It can't get rid of the excess heat under the bonnet when its stud still. If it was my car i would also get a new water pump and fit a new one, it could be suffering from cavitation (froffing the water) it does sound like the fan to me though.

[nick@dunsdale]

Hi everyone, I am having an overheating problem that seems to be baffling the mechanic.
It is a wolseley 1300 engine that hasn't seen much use since it was rebuilt (maybe 200km, in storage for about 4 years).

Symptoms
- overheats at idle if started from cold, in about 10-20 min.
- cools down when driving, starts to heat up again if stuck in traffic. revving high/using low gear helps.
- on the motorway, it will usually hover around 3/4, running the heater brings it down a bit. on downhills the gauge sometimes reads below normal.

Steps taken so far
- flush radiator (was full of some slimy stuff - product of two incompatible antifreezes?)
- replace thermostat
- check gauge is correct
- check hoses
- check water pump impeller gap (it is a new pump with a pressed steel impeller)
- leakdown test (ok)
- check timing (was overly retarded due to wrong timing marks) & carbs (running fine)
- check heater (works fine)
- check radiator is working, with thermometer
- check fan/water pump pullies (they are the smaller ones)
- fan is a plastic one

The engine runs well apart from the overheating problem. Oil pressure is about 65psi.

Only think I can think of is a blocked water passage between head and block?

Also, if anyone in the Christchurch/Otago NZ area has a good used front bumper with overrider holes, mine got pranged in the earthquake. Also after a new or rebuilt upper right door hinge.

Is there not an important one missed out here

" temperature sender unit"
though would not make the engine overheat, it would give the false impression that it was overheating

i would also try bypassing the heater just to rule that out just join the two pipes with a bit of copper pipe or similar.

maybe try even running without thermostat, just to see if makes any difference.

is there excessive pressure within the cooling system, are the pipes hard and solid to squeeze when the engine is hot an in a state of apparent overheating.

[savetheminis]

OK, I have confirmed the fan is the right way round. It's the same kind of plastic fan that has never caused me any trouble before on other engines.
Also the overheating has been confirmed by thermometer so it isn't the gauge.
There is a bypass hose in place.
I am going to get them to try a different water pump before taking the head off.

So... there is not enough cooling at idle (low fan/pump speed, low power) and there is just enough when driving at high rpm in second gear (high fan/pump speed, low-ish power).

Fan is on the right way around, radiator is 3-core, and has been cleaned out, hoses & heater are ok.

Water can't circulate/reach some part of the engine enough to cool it properly unless the water pump is working at high rpm? Some sort of obstruction opens up or allows enough water to flow through at higher pressure?

[IAIN]

You say you have cleaned the radiator out but not the engine.

Would it be worth trying a rad/engine flush before you dismantle anything ?
Run the engine with the cleaner in, when it cools, flush it out by undoing the hose at the water pump and removing the temprature sender,refit the hose. Then get a your power washer and hold the nozzle tight up to the temperature sender hole in the head and blast it through. Take the radiator cap off and watch the water untill it runs clear.

If that makes no difference it probably needs a new 2 core radiator.