keel cooled 1.5 not getting hot enough

[Karen Lea Rainey]

This week my end cap developed a small crack and the engine started to lose water from the perished rubber.

it normally operates at at about 75c, when it was losing water it got as high as 120c, pulling over to moor and inspect i could see steam/spray coming from the end cap.

having replaced the rubber cap and refilled with both coolant and water, i restarted the engine and ran the engine for about an hour and took it for a 2 hour journey yesterday.

the temp only climbs to about 55c, just registering on the gauge.

i have removed all hose clips one at a time and filled up in turn to the highest point before the filler cap.

there is a clear sign of water being pumped around the system and the amount of water in the heat exchange looks quite stable.

 

my next check is, as the thermostat would have opened to past its maximum could it have stuck in the fully open position hence no pressure / heat would build up to the previous levels and the water would continue to circulate unpressurised as it were to some extent.

there is no calorifier in the system just the skin tank with no bleed valve on it.

your comments would be welcome to me.

[RLWP]

The thermostat might have stuck open. However, did you loosen one of the blanking plugs in the cylinder head when you filled up with coolant?

 

Richard

[Karen Lea Rainey]

No i didnt touch any blanks just the end cap initially, then rechecked every hose in succession.

[RLWP]

It isn't easy to get the air out of a 1.5 head when you are filling it. If you have a calorifier it is often plumbed into the head via one of the blanks, so that bleeds the head. If you haven't it's best to undo one of the blanking plugs when you are filling

 

If you don't, a temperature sender sitting in air reads low.

 

Try undoing one of the plugs to find out if the head is full of air or water

 

Richard

[pete.i]

Hi all

 

Richard I am having a similar problem at the moment. I do know about the difficulties with bleeding the head on a BMC 1.5 but usually what I do is undo pipe connectors and jubilee clips. Sit waiting for the bubbles to come up through the coolant filler cap with the engine running and eventually it bleeds itself and everything is fine untill I get another problem with the coolant system or I do a coolant change. I haven't seen any blanking plugs on my engine that I can unscrew to bleed the head. There are blanking plugs but they are the compression type and don't unscrew. It would be a lot easier if there were unscrewable blanking plugs so could you tell me, roughly, where it is please. I should have asked you to point them out when you visited the other day and we were looking at my spare engine.

[Karen Lea Rainey]

Thanks richard, will look at that next week now, back to work now until tuesday, bah

[RLWP]

I have a BMC 1.5 head here at the moment, I'll take a picture tomorrow

 

It shouldn't happen, the thermostat seem to prevent air getting through when it is cold. I know some varieties of themostat had an air bleed, and maybe after market ones have got fitted that don't

 

Richard

[Tony Brooks]

Carefully drill a 3mm hole in the moving disk of the thermostat then it will be like the old ones except it will not have a jiggle pin in it.

 

 

Original heads have a 5/8AF (I think) hexagon plug at both ends of the head slightly offset to the right. One probably has a calorifier connection on it. The back one is almost obstructed by the fuel filter bracket. Some modern heads made abroad may not have both these plugs.

Edited March 12, 2015 by Tony Brooks

[RLWP]

I liked that jiggle pin, I remember that pin being in the static part - that's where I would drill a hole

 

Richard

Edited March 12, 2015 by RLWP

[Tony Brooks]

I liked that jiggle pin, I remember that pin being in the static part - that's where I would drill a hole

 

Richard

 

It was on many but some had it in the valve. I am not so sure how much clearance a waxstat has between the seating on the head and the inner edge of the flange so without looking bat an individual engine I thought it would be best to say the moving part. I also seem to remember the flange on many waxstats has a circular raised pressing in it for strength that might may drilling it s bit tricky, but not impossible.

[RLWP]

This is a BMC 1500 head:

 

 

This one has two bleed plugs, one at the front:

 

 

and one at the rear:

 

 

Richard

[pete.i]

Thanks for that RLWP. The one on my boat has one of the cooling pipes attached to the back one and the front one is hidden underneath the pipe that goes to the heat exchanger. I found that one yesterday because I changed the water pump and had to remove that pipe.

 

There are two on my spare engine as well but they have a screwdriver slot and are, more or less, flush with the head surface. Anyway thanks again, now I know.

[Tony Brooks]

 

Original heads have a 5/8AF (I think) hexagon plug at both ends of the head slightly offset to the right. One probably has a calorifier connection on it. The back one is almost obstructed by the fuel filter bracket. Some modern heads made abroad may not have both these plugs.

 

 

Poor old sod - memory playing tricks again! Offset to the left. I guess its the 2.2 with the back one almost under the fuel filter bracket.

[RLWP]

You aren't going to make me dig out a 2.2 head are you? It weighs a ton!

 

Richard

[Tony Brooks]

No, for all I know some 1.5s may have had them where I said at one time - maybe it was the B Type petrol engine.

[RLWP]

And a B series - my poor back...

 

That one is in the shed, at least the 2.2 is in the workshop

 

Richard

[Bee]

Often wondered what those plugs were. Not sure where the temp. gauge sender is located on your engine but on my Beta it is pretty much the highest point in the circuit and where air can collect, this can give a false reading.

[MtB]

That's a lovely shade of blue you've painted that head Richard...

[Troyboy]

That's a lovely shade of blue you've painted that head Richard...

[/

Obviously not a stickler for originality as BMC diesel engines were painted green unless it was factory reconditioned unit in which case they were painted gold .

[pete.i]

 

That's a lovely shade of blue you've painted that head Richard...

[/

Obviously not a stickler for originality as BMC diesel engines were painted green unless it was factory reconditioned unit in which case they were painted gold .

 

Yes my spare engine was a horrible army type green mixed with rust. Reminded me of my time in the army driving trucks in that same horrible green, I think they called it khaki in them days. Anyway I painted the block blue and the head silver mainly because that was what colours Halfords sold for heat resistant engine paint. paint.

[RLWP]

That's a lovely shade of blue you've painted that head Richard...
[/
Obviously not a stickler for originality as BMC diesel engines were painted green unless it was factory reconditioned unit in which case they were painted gold .

Depends what you mean by original. There's no green or gold paint on this engine, there was blue from the mariniser. So that's what it is going to be

 

Richard

 

We won't talk about the Post Office red SR2 in the workshop

Edited March 15, 2015 by RLWP

[pete.i]

Sorry it wasn't called khaki on them army trucks although we did have khaki. Olive drab I think was the official quarter master stores labeling.

[RLWP]

Was that on the sign behind the door?

 

Richard

[Karen Lea Rainey]

Just to reply to this original post, Temperature not getting hot enough,

 

I purchased a new thermostat from asap supplies a 74c one with a gasket, cost £12 inc postage,

 

When i took the thermostat housing off the engine, i couldnt beleive it, there wasnt a thermostat in it!!!

 

Put the new one in and hey presto within about 15 mins on tickover the temp goes up to about 75 c and stays there., even been a couple of miles to the next winding hole and it looks good to me.

 

ps just decoked my engine aswell, but i will start a new thread to tell you about it.

[RLWP]

A nice, cheap result there - good work!

 

Richard