BMC engine overheating

[Tony Brooks]

I don't think there is space for any in the block on the manifold side. The two side plates come a long way up the cylinder block and the push rod cavity goes all the way to the head. Happy to be proven wrong though. There are some in the head though but on the injector side, possibly 2.

[MtB]

5 minutes ago, Alan de Enfield said:

He has already posted that he has located six

No he hasn't! He said the manual appears to show six but he isn't sure. 

[Mad Harold]

23 minutes ago, Tony Brooks said:

I have no idea what you mean by "a non-shut off thermostat". If you mean one with a bleed hole in the valve disk (with or without a jiggle pin) then its just a standard thermostat as opposed to a bypass thermostat that I doubt would fit into a 1.5.

I think but can not be sure, that there is one core plug behind the backplate but that may depend upon how old the engine is, who's marinisation it is and which gearbox is fitted. The lien diagram here http://www.ioffer.com/i/bmc-1-5l-diesel-engine-bmc-5-1-sea-lord-marine-engine-service-manual-508711607

on the right of the photo shows a sort of clear rectangle in the back of the block - that's a core plug.

An 82 degree thermostat is way too hot for a direct raw water cooled BMC 1.5, you need nothing much above 70 degrees. I would try for 62 degrees.  82 is the standard marine stat for a heat exchanger engine so are you sure its not a heat exchanger engine? By all means post a photo.

Don't worry but just be aware that all may not be a straight forward in the longer term as you think it is. There were loads of direct raw water cooled 1.5s (both petrol & diesel) in the 1970s. Once you are sure it really is direct raw water cooled then please fit a cooler thermostat to avoid a  furred up and cracked cylinder head

 

PS if you do want to post a photo so we can confirm it is/is not direct raw water cooled I would suggets that you start a new topic in the BMC section so it does not confuse the OP.

Thank you Mr.Brooks for taking the time to answer. The thermostat I fitted is described by ASAP supplies as "without shutoff"I assume that means it will not fully close in the event of failure,thereby stopping all cooling water circulating. ASAP supplies only list two thermostats for the BMC 1500,82 degrees and 74 degrees.

It is definitely direct raw water cooled.

I take your point about confusing the original query.

[Tony Brooks]

You may find you get a wider choice of thermostats from a Motor Factors. They are nothing special.