Roxylass Posted July 26, 2021 Report Share Posted July 26, 2021 Came in from fishing yesterday Lifted the engine box lid as I saw Some light smoke engine hotter than its ever been SR2 cut out when I put it down to tick over let it cool down and pulled the dipstick showing correctly on the dipstick mark had latex gloves on The last inch of the dipstick actually Burnt my fingers The oil looks good no smell of diesel There is a film of oil on the exhaust manifold Puzzled Link to comment Share on other sites More sharing options...
Yellowback Posted July 26, 2021 Report Share Posted July 26, 2021 You fishing on the local duckpond, or thrashing the engine to within an inch of its life fighting against a rising tide with an oversize beam trawl in tow ? Link to comment Share on other sites More sharing options...
Roxylass Posted July 26, 2021 Author Report Share Posted July 26, 2021 Half throttle 4 miles out 4 miles back in Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 The TV implied it was very hot your way yesterday, so if it's air cooled are you sure there is adequate air ducting for the cooling air? The oil normally plays a big part in cooling the pistons and I doubt that you have an engine oil cooler, so with poor or no airflow around the crankcase to cool it, I would expect hotter than normal oil it elevated ambient temperatures. Engine oil temperatures can go well over 100C in engines. Indeed they should to boil out any condensation, otherwise the oil can turn itself into a greasy type substance. Link to comment Share on other sites More sharing options...
Roxylass Posted July 26, 2021 Author Report Share Posted July 26, 2021 Half throttle 4 miles out 4 miles back in Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 2 minutes ago, Roxylass said: Half throttle 4 miles out 4 miles back in ? If the ambient temperature was as hot as the TV suggested, then the oil will be hotter than at a lower temperature. I note you don't address the cooling duct adequacy. Link to comment Share on other sites More sharing options...
Roxylass Posted July 26, 2021 Author Report Share Posted July 26, 2021 The fan in front of the gear box Also a 9inch x 6inch cut out On the engine box port side Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 So is that an open slatted or solid box? Is the cooling exhaust air ducted to the 9 x 6 cutout, and if so how does the cool air get into the fan? Link to comment Share on other sites More sharing options...
nicknorman Posted July 26, 2021 Report Share Posted July 26, 2021 (edited) 23 minutes ago, Roxylass said: Half throttle 4 miles out 4 miles back in Bear in mind that the “throttle” isn’t really a throttle, it is an rpm selector for the governor. The governor will send in as much fuel as necessary to achieve the set rpm. So for example if the prop had some rubbish on it that created a lot of drag, the governor might be sending in nearly maximum fuel to achieve a middling rpm, and thus a lot more heat is created. Edited July 26, 2021 by nicknorman Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 Even without muck on the prop, if the cooling is inadequate the engine may well overheat and partially seize, so doing what Nick describes. The failure to idle tends to suggest a stiff engine. Link to comment Share on other sites More sharing options...
Roxylass Posted July 26, 2021 Author Report Share Posted July 26, 2021 Half inch plywood engine box Only outlet is the one I described As far as I knew the fan sucked Cold air in circulated the engine Any air coming from the exhaust I would have thought to be far to hot Link to comment Share on other sites More sharing options...
nicknorman Posted July 26, 2021 Report Share Posted July 26, 2021 All the lister aircooled installations I’ve seen have an inlet grill and an outlet grill. If there is just one grill then it’s hard to see how there can be adequate cooling. It sound as though this is a sea going boat so obviously engine venting is a bit more complex than for a canal boat (need to keep the sea out!) but I think you need to consider the entire airflow path from outside to outside, via the engine/fan. 1 Link to comment Share on other sites More sharing options...
Arthur Marshall Posted July 26, 2021 Report Share Posted July 26, 2021 (edited) When did you last change the oil? My Lister cuts out when it overheats, usually due to disel contamination in the oil but also if the oil is so old it's stopped working. Before I corrected the ducting for the hot air eject it also used to overheat in very hot weather as not enough cool air got in and I had to drive with a deck board up - still didn't like last week much. If the cutout for the air is the only one, is there any ducting at all? (Crossed with Tony's below) Edited July 26, 2021 by Arthur Marshall Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 (edited) 17 minutes ago, Roxylass said: Half inch plywood engine box Only outlet is the one I described As far as I knew the fan sucked Cold air in circulated the engine Any air coming from the exhaust I would have thought to be far to hot OK, so do you understand air cooling. The COOLING system needs cool air delivered to the fan and the DUCTS to direct that hot air away to outside the engine case. Without the ducting, the fan will just recirculate the hot air back through the cooling fins so you get exactly what you found. The ducting must not leak hot air into the engine bay. The Lister marine manual explains all this. In fact, experience tells me it is also a good idea to duct air from outside the case direct to the inlet manifold. The engine exhaust pipe has nothing to do with the cooling air exhaust. Luckily for you those engines are very robust plus some, so if you sort out the COOLING EXHAUST AIR ducting and vent it is unlikely to have suffered from the partial seizure. Edited July 26, 2021 by Tony Brooks Link to comment Share on other sites More sharing options...
Roxylass Posted July 26, 2021 Author Report Share Posted July 26, 2021 Tony I shall take some photos of inside the box today you will see a clearer picture of what I am trying to explain Your help is appreciated as always Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 It is simple. Your cooling "fan" is part of the flywheel and as such without an expensive custom-made cowel to fit around it with a spigot to connect to a cool air inlet duct it's best to just let it suck COOL air out of the engine bay. But to do this it needs an easy access for the air into the engine bay. This is where your 9 x 6 hole comes in to use. The "fan" blows the cool air into the air casing around the engine, through baffle plates that ensure an equal amount of air is blown through the fins on each cylinder. That air gets hot as it cools the cylinders. The hot air should exit the air casing via another thin metal shroud that allows you to connect large air ducts to the connected that then run to another hole or holes in your engine case. Preferably on the opposite side to the inlet hole. Thus, the hot air exiting the engine cooling system is kept well away from the cool air being drawn into the case or being recirculated through the cooling system. You need two large holes in the case unless the case is slatted all around as per the Lister specs. One to let cool air into the engine case and one to allow ducted hot air to exit the case. If you don't do that you WILL be subject to partial or a full engine seizure and if the SR has steel inserts in the pistons like the SLs a steel insert might pop out and jamb the engine. Possibly bending valves, push rods and/or the connecting rod. I think (but don't know for sure) that the SR does not have such inserts. 1 Link to comment Share on other sites More sharing options...
Machpoint005 Posted July 26, 2021 Report Share Posted July 26, 2021 (edited) 2 hours ago, nicknorman said: All the lister aircooled installations I’ve seen have an inlet grill and an outlet grill.<< Without a fresh air inlet and an air discharge, the hot air will be going round and round and round the engine compartment - and the heat doesn't get lost. That applies to any air-cooled engine. The amount of cooling air required is a great deal more than the engine's combustion air requirements. This applies to any air-cooled diesel, not just marine ones. Edited July 26, 2021 by Machpoint005 Link to comment Share on other sites More sharing options...
Roxylass Posted July 26, 2021 Author Report Share Posted July 26, 2021 Arthur Do you have any photos of your engines ducting could be helpful Other wise going to have to cut slots In the front of the box and enlarge The holes I already have can't see how I would be able to fit ducting in that box Link to comment Share on other sites More sharing options...
David Mack Posted July 26, 2021 Report Share Posted July 26, 2021 This is a ST2, similar to your SR2. Cooling air is drawn in through the grill between the engine and gearbox in the centre of the photo, and the hot air leaves the engine via the red metal duct and into the canvas trunking. You should have something similar to the red duct leading directly to the outside of the engine case. Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 Here is the manuallstrsrm.pdf Pages 6 to 8 Link to comment Share on other sites More sharing options...
Roxylass Posted July 26, 2021 Author Report Share Posted July 26, 2021 Very similar indeed I will see where I can get a canvas Trunking Link to comment Share on other sites More sharing options...
Arthur Marshall Posted July 26, 2021 Report Share Posted July 26, 2021 I used a bit of central heating ducting with a face plate on the original box, which had canvas ducting originally. With a cruiser deck, the canvas got wet and sagged and stopped chucking the air out. When I bought the boat, it had obviously caught fire at some stage too! Pics aren't very good as access is tricky. Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 I think the plate your two ducts are fitted to is/was a Lister part, except I have seen the crimped aluminium ducts used in place of your plastic ones. My guess is that the OP does not that the adaptor needed to fit either the ally, plastic or canvas ducts. Link to comment Share on other sites More sharing options...
Yellowback Posted July 26, 2021 Report Share Posted July 26, 2021 8 minutes ago, Tony Brooks said: My guess is that the OP does not that the adaptor needed to fit either the ally, plastic or canvas ducts. But I'd bet she's capable of fettling something suitable now she's seen what's needed. Link to comment Share on other sites More sharing options...
Tony Brooks Posted July 26, 2021 Report Share Posted July 26, 2021 16 minutes ago, Yellowback said: But I'd bet she's capable of fettling something suitable now she's seen what's needed. I think the gender you assume is from the boat name, the OP gives his sex as male. Link to comment Share on other sites More sharing options...
Featured Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now