From one extreme to the next

Well I'm never too proud to admit when I have been a complete and utter plonker and I do sometimes have a habit of jumping to the worst case scenario but I discovered yesterdays cause of the dramatic temperature rise in my engine and it was directly related to one fundamental component of a coolant system.......... the coolant itself, or lack of it! It was VERY low, about 2 litres to be exact :oops: :oops: :oops:

I decided to check the operation of the water pump first so removed the blanking cap on the rad (the pressure cap is on the expansion Bottle) and when I looked into the radiator I couldn't see the water level :shock: I was expecting it to be flush with the top because my expansion tank had some coolant in it. I already had some mixed up so started to top it up and I reckon I had to put about 2 litres into it :shock: I ran the engine up the temperature and waited for any air to 'burp' out. I left the car ticking over for about half an hour and the temperature gauge stayed firmly in the centre right between the 8 and the 5 :D

I will admit that since fitting the expansion tank I would check the level in that and assume all was well, evidently it wasn't. I fitted the tank as per other members cars but always found that if I topped it up to the line it would drop and be sitting just above the bottom inlet pipe after a run. Talking to some SD1 owners they too exprience this and even went so far as to fit a catch tank to collect the coolant that was forced out of the expansion tank overflow. Quite clearly my expansion tank wasn't feeding into the rad and over time the water level has dropped :? This was one of the main reasons for fitting the tank as I was having to frequently top up the radiator and assumed this was due to coolant coming out of the vent (I will say that I am not aware of any coolant leaks and even after yesterday there isn't any evidence of head gasket failure). How often would I expect to top up the radiator without a tank fitted?

Upon advice and the practicalities of it I fitted the expansion tank as low as possible but it doesn't seem to feed into the radiator so what I have done is fit the pressure cap back on the rad and the blank one on the tank and will monitor coolant levels. While I was poking around with the engine running I noticed that the water pump pulley has a slight wobble backwards and forwards as you view it side on like it isn't running true :? Could this be a case of it not being mounted properly or wear inside the pump itself? I did put a screwdriver to it and put my ear to that and had a listen and it sounded ok, there was a consistant ticking nosie, obviously the impellor turning but then I have nothing to compare to, should this noise just be a whirring sound and the sound of coolant rushing through?
 
Mikep said:
How often would I expect to top up the radiator without a tank fitted?
Click to expand...

You shouldn't have to top it up at all. Back in the day I was looking for something to smoke around and bought a 3500S with a small bit of damage on the front that had bent the bonnet and pushed the slam panel back. I roughly pulled things back into line, but for reasons I can't remember the bonnet ended up bolted down. Once it was checked initially I never opened the bonnet again......

Mikep said:
While I was poking around with the engine running I noticed that the water pump pulley has a slight wobble backwards and forwards as you view it side on like it isn't running true :? Could this be a case of it not being mounted properly or wear inside the pump itself?
Click to expand...

Those pulleys often get bent. Check for play in the water pump by rocking the fan blades. (If you have them....)
 
DaveHerns said:
I have done is fit the pressure cap back on the rad and the blank one on the tank
Click to expand...

I think this is the way it should be .
Click to expand...

No it isn't , Pressure cap on the expansion tank , blank cap on the rad if you want it to function as an expansion tank .
 
stina said:
DaveHerns said:
I have done is fit the pressure cap back on the rad and the blank one on the tank
Click to expand...

I think this is the way it should be .
Click to expand...

No it isn't , Pressure cap on the expansion tank , blank cap on the rad if you want it to function as an expansion tank .
Click to expand...

I concur Stina, I have swapped it back round for the time being so effectively the expansion tank is now a catch tank for the radiator overflow.

Stina, your expansion tank position was one I tried to mimic, I take it yours feeds into the rad perfectly fine?
 
Hi Mike .
Yes i fitted mine as high as the underside of the bonnet would allow . To fill it i filled the rad first through the rad filler then let it run for a while , Then filled the expansion tank about half full , Then the clever bit , loosen the blank cap on the rad a little and seal your mouth around the expansion tank and blow into it forcing the air out through the top of the rad . When it's up to temp it'll blow out what it doesn't want and the level will settle down after that . Good luck :D
 
stina said:
Hi Mike .
Yes i fitted mine as high as the underside of the bonnet would allow . To fill it i filled the rad first through the rad filler then let it run for a while , Then filled the expansion tank about half full , Then the clever bit , loosen the blank cap on the rad a little and seal your mouth around the expansion tank and blow into it forcing the air out through the top of the rad . When it's up to temp it'll blow out what it doesn't want and the level will settle down after that . Good luck :D
Click to expand...

Excellent, I didn't think of dong that way, thanks for the tip Stina :D
 
MikeP wrote,...
How often would I expect to top up the radiator without a tank fitted?
Click to expand...

Hi Mike,

With my original 10.5 : 1 engine, coolant level would always fall over time, especially so during Summer. After running and then with the engine shut off, heat would build within the cylinder heads leading to an increase in pressure with the resulting purge from the overflow. This occured both with the original tin gaskets and later with the composite gaskets.

In contrast, my 4.6 is the complete opposite with no change in coolant level at all.

Ron.
 
SydneyRoverP6B said:
MikeP wrote,...
How often would I expect to top up the radiator without a tank fitted?
Click to expand...

Hi Mike,

With my original 10.5 : 1 engine, coolant level would always fall over time, especially so during Summer. After running and then with the engine shut off, heat would build within the cylinder heads leading to an increase in pressure with the resulting purge from the overflow. This occured both with the original tin gaskets and later with the composite gaskets.

In contrast, my 4.6 is the complete opposite with no change in coolant level at all.

Ron.
Click to expand...

That's interesting Ron because thats what I was experiencing. As I say I will keep a close eye on the level to ensure I'm not losing it anywhere else.
 
I still don't agree . With the pressure cap on the radiator , any excess water should be expelled into the expansion tank and sucked back when the water cools and it's volume reduces .However you'd need an watertight seal on the radiator cap as well as the pressure seal.
Think of how the expansion tank works on your central heating system .
 
The extra tank is to increase the capacity of the system, and that won't be the case if all it's doing is catching anything that's being blown out under the pressure cap on the rad (which shouldn't be happening anyway). With the pressure cap on the tank, and a blank cap on the rad, it means the rad can be completely filled, with the air gap to allow for expansion in the top of the remote tank instead.
 
No Dave. The outlet to the expansion tank is on the atmospheric side of the pressure cap when that cap is on the rad. So the expelled water will reach the expansion tank OK but be unable to return to the rad. Correct arrangement is plain cap on the rad and pressure cap on the expansion tank. Unless you use the tricksy sort of pressure cap that many Japanese cars carry - and hence is the norm in NZ - which has an extra valve....

Chris
 
That makes it a header tank rather than a plain expansion tank. I can't help but think Rover would have added such a tank if it was needed .There was another example of a V engine and low mounted radiator in the Mk 4 Zodiac/Zephyr range and that had a header tank
My V8 runs on 33% old type blue antifreeze, mechanical fan , can't remember if the thermostat has a bleed hole or jiggle pin and once the coolant is about 1" down from the top of the rad , no more escapes . Maybe I'm just lucky...

I was indeed thinking of the Japanese type cap with the extra seal. I thought I'd seen them on some UK cars .
 
Didn't the BMC 1100/1300 range have a non-pressurised expansion tank of the type I've described ?
On the topic of the Rover V8 being a "dirty" engine surely the source of the dirt must be piston blow-by which as these engines were built with graded pistons ( I think Harvey said that) . So the dirt is a symptom of wear, not design ?
 
The Rovering Member said:
Whatever it is, with one fitted, the radiator remains absolutely brim-full. Which is just how I like it.
Click to expand...

Precisely the reason I fitted one although it doesn't seem to be working at keeping the rad full :( , a job for the weekend I think :roll:
 
DaveHerns wrote,...
On the topic of the Rover V8 being a "dirty" engine surely the source of the dirt must be piston blow-by which as these engines were built with graded pistons ( I think Harvey said that) . So the dirt is a symptom of wear, not design ?
Click to expand...

Hello Dave,

The process by which the engine had been run in will be quite influential in terms of seated piston rings and blow by. The 14 bolt cylinder heads and specifically the outer row of bolts can allow combustion gases to leak into the lifter gallery. Contaminated oil, increased engine wear and sludge all result, especially when the oil and filter are not changed frequently.

When you look inside the oil filler cap on your Rover, what colour do you see? Can you see grit on the rocker assemblies? How often do you change your oil and filter? How many Miles has your engine seen?

Ron.
 
DaveHerns said:
Didn't the BMC 1100/1300 range have a non-pressurised expansion tank of the type I've described ?
Click to expand...

Nope, plain cap on the rad and spring loaded on the expansion tank.
They are fitted low down, but that doesn't change the way they work.
 
My engine hasn't been apart in the years I've had the car so mine isn't a good example to use
I do notice that when I pull the dipstick out the oil on it is clear but always black when I drain it .So maybe the oil sticks to the outside of the engine?
 
You must log in or register to reply here.
Back
Top