Search the Community

I have an old BMC 1.5 / Thornycroft 90 fitted to my boat that is raw water cooled, unfortunately it is not pulling enough water through and has caused the engine to overheat leaving a trail of white steam behind me. I have been on the Jabscoshop website looking for a service kit but the only pump they show for this enging is a pedestal mount and the one fitted to my engine is engine mounted and crank driven. Ive tried to contact Jabscoshop for advice but to no avail can anyone point me in the direction of someone who can supply advice and a service kit for my water pump Cheers A

Hi again, I'm still trying to get the boat to run nicely, apart from the plumes of smoke, which I publicly apologis for, (I'm hoping it's to do with the prolonged bedding in period and that it will settle down to an acceptable level once the boat has a few more miles under it's belt) it still overheats. I think an airlock got purged during this afternoons trip as, initially, the first skin tank was warm, whereas the second tank was stone cold. After this airlock was belched out, the second tank started to warm up, but by then, I'd discovered the Cambrian Wharf visitor moorings were full, so headed back to Sherborne Wharf. Basically, I think the coolant is struggling to travel around the circuit because the engine pump can't push the huge volume of water around the numerous 90 deg bends in the circuit between engine and skin tanks. Does it sound sensible to add another pump between the starboard and port skin tank? I'm thinking of fitting a thermostatically controlled electric one as I think it would be easier to plumb in, but, if a mechanical pulley driven one is more suitable, I'd go with expert opinion. If this is a sensible mod, what pump make/type would get your vote? The external hoses are all 32mm id except for restrictions into and out of the engine and gearbox oil cooler heat exchangers. At the moment, and it was only a very short trip, it seems that running at anything over tickover causes overheating but it was stable cruising at tickover. Failing that, is it possible to convert to raw water cooling or is that just changing one set of problems for another? Thanks in advance Robert

This was a recent job, and I would rather not reveal who the boat belongs to so as to avoid embarrassment. My heart sank when I took the rocker cover off and found this. This is the valve clearance as found: The clearance here should be around 0.015", this must be four or five times this. Notice how 'dry' the rockers are. The pushrod end looked pretty nasty too: Several of the adjusting screws had been running completely dry, producing the characteristic red frettage powder: This looks like a classic oil feed problem. There could be a variety of causes for this, starting with wrongly assembled rockers. One of the pillars has an oil feed in it to line up with the feed in the head. You can see the hole between the studs at the bottom: The right pillar was in the right place, so next stop is at the head gasket Bingo!: This isn't right, the oil feed to the head should be here. Sure enough, under the head gasket was: The oil feed! What's wrong is that the gasket is on upside down, the hole in the gasket being at the wrong end: And it was bloody glued on as well!!! Anyway, net result was that no oil got to the rockers, so the bearings wore out. Naturally the shaft was completely wrecked too. Fortunately, the bushes, rocker shaft and valve guides are the same as for a BMC 1.8 in an MGB - meaning car prices rather than boat prices! This is a new bush: They are supplied undersize and have to be reamed to size when installed. I took some of the meat out first in the lathe: There are two oil feeds in the rocker. One sprays oil about to lubricate the valves and springs, the other feeds to the top of the pushrods. That feed has a plug in the end: Which had to be removed: so that a hole could be drilled through the bush: before finally reaming to size: I made up and fitted some brass plugs to finish the oilways, sorry no photo. Richard I can't get any more photos into this posting

Hi, I'm still struggling with the engine in my 40ft boat, it's a 1.5BMC with bowman header, skin tanks and dry exhaust, smaller diameter water pump impeller which looks to be in good condition. 82 thermostat fitted which tests ok in a pan. After welding up a couple more suspect areas on the starboard skin tank I took the boat out for a spin around Birmingham on Saturday. The trip was a bit of a challenge. The water leaks have all been fixed and the system was bled fully, each skin tank has a bleed screw on the top From our mooring in Sherborne Wharf we got as far as the bridge before the engine cut out, a whole 100yards maybe. It would run ok in neutral but stall as soon as drive was engaged. After pulling up outside Banatynes, getting a late lunch and letting off a bit of steam, we discovered the prop was fouled. So, with that cleared we carried on, the idea being to complete the Lozells Loop as a test run. However as we got around the corner it was apparent there was still an issue with the cooling system, the gauge steadily climbed up and up to the red zone so I shut the engine down. We pulled up, had a check of the system and discovered the port skin tank was stone cold whereas the starboard was warm. The pipe between the two was cold. Last night I drained the tanks, took off all the pipes and gave each tank a thorough flushing for 20 minutes. As I'd been through a similar exercise recently, I hadn't expected to see much rust and sure enough, the water ran crystal clear throughout. One thing that occurred to me is that the gearbox and engine oil coolers are probably not in the best part of the system. They sit, in series, between the port skin tank and water pump with various reducers and adapters in the way. I'm sort of hoping that between the bore differences and the restricted flow through core of the heat exchangers, the pump struggles to lift the water up and around the system and is probably just cavitating. The starboard tank (I assume) heats up through thermo syphoning. If this is the case, a bit of re-engineering will hopefully suffice. Assuming the cooling system is running properly, is there any need for an engine oil cooler? Is there a better place in the circuit to run the coolers? I noticed a picture here recently where the cooler was plumbed through the end caps of the header tank. Any advice or pictures of successful cooling systems will be gratefully recieved. Thanks in advance Robert

Hi Folks. First post in here. Actually first boat I've owned, and first engine I've attempted to fix. So appreciate all the help I can get. I have 3 out of 4 working injectors. I also have fuel being delivered to all 4 fuel lines by the fuel pump. But for some reason, I have no fuel coming through the injectors. I've put a video here to demonstrate: https://youtu.be/8Df_UCQf6T8 I can think of a few reasons why this might be, including no lack of pressure from the fuel pump. But before I go taking the fuel pump apart or replacing it, are there other reasons this might happen? Many thanks in advance.

Hi all! So, I really hope one of you out there might know where I could find some of these old engine mounts. They are the metalastic top hat type with three bolts that screw into the bell housing. I've seen that there are some really useful previous threads on here that have exactly the same set up as me with these rear mounts, the bobbin forward ones and the 4" coupling from a mini driveshaft. Unfortunately ASAP and Calcutt don't have them any more and, am I right in saying that Thornycroft don't exist now? Their website doesn't seem to anyway and it's been a long time since I've seen a yellow pages. My mounts are very dead and that has killed the shaft coupling, which I also can't find as it has a register of 85mm, and everything now seems to be 2.5" I think I can solve all of this with a new 5" OD shaft coupling, flexi coupling and then getting an adapter bobbin turned up to go from that to my gearbox flange, which is 5.5" and also has a strange 85mm register. But... unless I can find some engine mounts none of it means anything. Please, any suggestions would be greatly appreciated. Do I try to get a mount turned up? or just mount it solidly? It's a pretty smooth engine after all. The old mounts have a lovely dusting of metal around them so I think any hope of re-using them has been put out of my mind. Many thanks in advance... now I'll try to add some pictures...

Hi all, I need to drain my fuel pump on a BMC 1.5 as I need to apply thread lock on the ideal pin that has a slight leak, any help would be greatly appreciated.