BMC 1500 thermostat query

[amanda and dave]

Hi all,

 

I removed the thermostat housing today in order to replace the thermostat only to find that there was no thermostat in the housing !

 

Would there be any reason why someone would remove the thermostat and not replace it ?

 

The only reasons I can think of are that someone either forgot to put a new one in or was just too tight to buy a new one however i'm wondering if there could be any other reason for it not to be fitted .

[RLWP]

If a boat overheats, the Old Gits solution is to take the thermostat out.

 

Richard

[amanda and dave]

Ive noticed it takes ages to get up to running temp but when it gets there its constant . Im also wondering if that's why the water flow to the calorifier is just a trickle and doesnt heat the water in the calorifier up because the thermostat is missing and right from start the engine water is running through the skin tanks

[cereal tiller]

If a boat overheats, the Old Gits solution is to take the thermostat out.

 

Richard

I examined a BMC 1.5 that made a loud clanging noise.

 

Number 1 Piston was actually colliding with the Cylinder head!

 

An unwise person had removed the thermostat several years before.

 

The Engine oil had never been able to reach normal running temperature.so the oil became Acidic and ruined the the little end bearing in the piston.

 

The full rebuild cost a lot more than a new thermostat!

 

 

CT

[amanda and dave]

Hard to believe that someone would want to save a few quid by leaving the thermostat out !!

[alan_fincher]

As Richard has said, some people have a misguided view that if an engine is in the habit of over-heating, (perhaps becuase the skin tank is not adequate for the use being made of the engine), that removing the thermostat will in some manner help this situation.

If doesn't, and it seems a misguided thing to do. As Richard says, when the engine is being worked less hard, (particularly if just left idling for long periods), it will never get to the operating temperatures it is designed for, and that can cause damage.

But I bet it was taken out to cure an at least a perceived overheating problem.

Some BMCs require a special type of thermostat known as a "bypass thermostat", which has an additional part hanging down that the more "regular" version does not. If looking down your empty thermostat housing, there is a hole directly below the stat, with a seat like a tap has, that looks like something can be pressed down in to it, then you probably need this special type, or it will still not behave as it should.

I'll see if I can find a picture I know I have posted before that shows the difference.

EDIT:

Normal thermostat on the left, "bypass" thermostat on the right.

My BMC 1800 requires the latter, and the flow to the skin tank will not work properly if the wrong type is used.

Edited April 29, 2014 by alan_fincher

[RLWP]

Ive noticed it takes ages to get up to running temp but when it gets there its constant . Im also wondering if that's why the water flow to the calorifier is just a trickle and doesnt heat the water in the calorifier up because the thermostat is missing and right from start the engine water is running through the skin tanks

Yes, all of the above

 

Richard

[amanda and dave]

thanks for all your answers so far guys

[LEO]

Hi

 

As a matter of interest is the engine raw water or keel cooled?.

 

L

[alan_fincher]

Hi

 

As a matter of interest is the engine raw water or keel cooled?.

 

L

As he talks about skin tanks, I have assumed raw water cooling is not involved.

[amanda and dave]

Regarding the normal and bypass thermostats , ive looked on calcutt boats website and it says that the one without the bypass is suitable for bmc's with a calorifier . Is the one with a bypass also suitable for bmc's with calorifiers ?

Edited April 29, 2014 by amanda and dave

[LEO]

As he talks about skin tanks, I have assumed raw water cooling is not involved.

Missed that one, I have new thermostat if the Op wants one, not sure what temperature, probably 82 degrees.

 

L

[RLWP]

Regarding the normal and bypass thermostats , ive looked on calcutt boats website and it says that the one without the bypass is suitable for bmc's with a calorifier . Is the one with a bypass also suitable for bmc's with calorifiers ?

Yes, but it may reduce the flow through the calorifier when the thermostat is closed

 

Richard

[Chalky]

I seem to remember in the BMC manuals for the 1.8 petrol that it explicitly states that either a thermostat or a plate with a hole in it has to be fitted to ensure that the cooling system works correctly.

[RLWP]

I seem to remember in the BMC manuals for the 1.8 petrol that it explicitly states that either a thermostat or a plate with a hole in it has to be fitted to ensure that the cooling system works correctly.

Which heater control?

 

Some of them close the flow to the heater off

 

Richard

 

MORE: Apologies, I misread what you wrote. Yes, it wouldn't get up to temperature without. Our Rover 75 is running cold at the moment because the thermostat is stuck open. As BMW chose to put it next to the driveshaft, it's been like that for ages

 

Richard

Edited April 29, 2014 by RLWP

[amanda and dave]

Out of interest what should be the normal running temp of a 1500 ?

[Chalky]

MORE: Apologies, I misread what you wrote. Yes, it wouldn't get up to temperature without. Our Rover 75 is running cold at the moment because the thermostat is stuck open. As BMW chose to put it next to the driveshaft, it's been like that for ages

 

From memory the thermostat assembly (plastic ones) on BMW family engines at that time were service items that were changed a a regular service interval. I assume you've got the M47 ( I designed the electrical architecture to fit into Freelander).

[RLWP]

That's the blighter - M47R. Presumably easier to get to on a Freelander

 

Richard

[Chalky]

That's the blighter - M47R. Presumably easier to get to on a Freelander

 

Richard

 

No. Complete PITA. From an electrical viewpoint you can fit any BMW engine, plug in the connectors and everything will work correctly. No need to modelise the engine or vehicle!

[Tony Brooks]

Out of interest what should be the normal running temp of a 1500 ?

 

 

Typically they use an 82 degree thermostat for tank or heat exchanger (fresh water) cooling so it will probably run a bit above that, say 85 degrees.

 

I think at least one mariniser fits a lower temperature thermostat 74 degrees I think) so that the water coming from the calorifier is marginally less likely to scald. So say runs at about 77.

 

A direct raw water cooled engine has I think a 62 degree thermostat although I would run without one in hard water areas. Experience suggests to me the 1.5 is too ready to fur up the head when direct raw water cooled and that causes cracking.

[amanda and dave]

Cheers Tony , thanks for your reply

 

Dave

[amanda and dave]

Ive now ordered a 74 degree thermostat and gasket from sussex classic car parts . Works out a around £5 cheaper than online marine spare parts suppliers .

 

Thanks LEO (Mike) for informing me that the bmc 1500 thermostats are the same ones that are used in mg midgets and mgb's

Edited May 1, 2014 by amanda and dave

[RLWP]

Cheaper than this?: http://www.ebay.co.uk/itm/MG-MGB-ROADSTER-OR-GT-74-DEGREE-THERMOSTAT-AND-GASKET-ANG3-/310932470716?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item486504fbbc

 

Richard

[Tony Brooks]

Also probably cheaper form your local motor factors

[Troyboy]

Ive now ordered a 74 degree thermostat and gasket from sussex classic car parts . Works out a around £5 cheaper than online marine spare parts suppliers .

 

Thanks LEO (Mike) for informing me that the bmc 1500 thermostats are the same ones that are used in mg midgets and mgb's

When you come to sell your boat you can say it has a MG thermostat fitted . That should impress those that know nothing about boats . Mine has an MGB sump plug washer, oil filter and rocker cover gasket fitted .