BMC 2.52l Thorycroft 154 advice

[Fisher34]

I have this engine in my seagoing Fisher 34. It’s the original 1979 engine. 1800 hours. I bought her in 2016. The exhaust was a total rebuild. Have serviced her yearly since and she has run smoothly. Noticed several perished connectors including that from water cooler to engine. That perished last trip out, last week, noticed engine overheat, switched off and we were towed back. Are there any experts on this type of engine who travel to Dorset to repair in situ? Would be happy to pay for an assessment. 

[Tony Brooks]

Do you mean perished rubber or corroded aluminium?

 

I would comment that the manifold cum heat exchanger looks more Polar than Bowman to me and Polar no longer exist. I am no expert on the BMC 2.5 but that thermostat housing looks nothing like the ones used by the official marinisers on 2.2s. It may be a Thornycroft special who are again no longer trading. If it is corroded alloy I fear this may involve extensive new parts unless you can find an aluminium welder who can repair/fabricate.

 

Lancing Marine list a few parts as do ASAP supplies.

[Fisher34]

Thanks for the reply. Aluminium is fine it was just perished 5cm rubber hosing attached by two jubilee clips each side. However would love to find an expert to take a look. Although I can easily repair that bit it’s just one of the perished rubber hose connectors. 

[Tony Brooks]

20 minutes ago, Fisher34 said:

Thanks for the reply. Aluminium is fine it was just perished 5cm rubber hosing attached by two jubilee clips each side. However would love to find an expert to take a look. Although I can easily repair that bit it’s just one of the perished rubber hose connectors. 

 

 In my view a waste of money apart from the fact that the hose you show will almost certain;y require either the thermostat housing or the elbow on the hear exchange removing and that is where the fun may start with alloy castings. Rubber hoses perish with age and when in contact with hydrocarbons (fuel & oil) so checking them and replacing as required is really a service procedure.

[Fisher34]

Why would the thermostat be damaged? In the picture the green filler cap is where the coolant goes. The leak was through the perished rubber. The temperature gauge showed a reduction in heat when we switched off the engine after noticing the rise in temperature. Is the thermostat likely to be housed near the perished rubber ? Any idea where one buys replacement heat resistant 5 cm ext diameter, 3cm internal heat resistant rubber for this sort of job ? 

[Tony Brooks]

3 minutes ago, Fisher34 said:

Why would the thermostat be damaged? In the picture the green filler cap is where the coolant goes. The leak was through the perished rubber. The temperature gauge showed a reduction in heat when we switched off the engine after noticing the rise in temperature. Is the thermostat likely to be housed near the perished rubber ? Any idea where one buys replacement heat resistant 5 cm ext diameter, 3cm internal heat resistant rubber for this sort of job ? 

I did not say the thermostat was damaged. I said that to replace that short length of rubber hose the thermostat HOUSING may have to come off or the elbow on the side of the manifold. If you can find some silicon hose of the correct size you might be able to cut the old hose off and fold the new one enough to get it into that small gap between the two metal [pipes bit that is by no means certain.

 

New you mention it so earlier waxstat thermostats had clips that jammed it fully open in case of an overheat because all waxstats tend to leak wax during an overheat so they no longer open soon enough. However if you fit the hose and run the engine up to temperature you will soon know if the thermostat has clipped open or it has lost wax. The former will give a very slow warm up and cool running temperatures and the later an over hot running temperature.

[David Mack]

1 hour ago, Fisher34 said:

Any idea where one buys replacement heat resistant 5 cm ext diameter, 3cm internal heat resistant rubber for this sort of job ? 

 

Ebay. Just search for "radiator hose" and you get loads of hits.

[Tony Brooks]

Probably any half decent chandlers or in longer lengths motor factors.