BMC 1.5 - overheated, clanking, stopped

[jhodgski]

Had my engine running on low revs for a while. Heard a clanking sound so went outside to check if wasn't coming from the engine bay. It was. The engine then stopped as I noticed the temperature up at / above 100 degrees C.

 

Am waiting for it to cool down now. What is the clanking sound likely to have been? (It sounded like someone clanging scaffold poles around.) And is this likely to be terminal?...

 

Re the cause, I was running the engine for some hot water, but it was barely warm after an hour. Does the mean the thermostat didn't open, due either to faulty thermostat or not enough water flow to open it?

 

Thanks,

James

[Tony Brooks]

Sounds more as if the coolant level was so low it could not circulate but you have not mentioned clouds of steam or burned paint.

 

Heat opens thermostats NOT water flow.

 

At a guess I suspect the clanking sound was the engine jumping about as it seized up BUT with no steam and no burned paint on the head that does not tie up. The clanking might have been a big end bearing but then I doubt the engine woudld stop very quickly, they normally run for some time before the wear gets so bad it starves the rest of the engine of oil so it seizes up.

 

You may be lucky and when it is COLD you refill it and find it runs well enough but it may just as well be damaged beyond easy DIY repair.

 

Were you running it in gear, if so maybe your prop is badly fouled and whatever fouled it was banging on the uxter plate.

 

 

[jhodgski]

Thanks, Tony. Sorry, yes, there was a lot of steam. Not sure if any burned paint yet.

 

But I topped up the coolant level before this trip (about 3 hours engine running time), so I'd be very surprised if it dropping too low had been the cause of the overheating.

 

No, it wasn't running in gear. I'll check the water (and oil) later this aft then try cranking her up.

 

Will post back then. Fingers crossed!...

 

 

[Alan de Enfield]

1 minute ago, jhodgski said:

But I topped up the coolant level before this trip (about 3 hours engine running time), so I'd be very surprised if it dropping too low had been the cause of the overheating.

It may be a longer term problem - if you have had to top the water up previously then it is going somewhere. (I have never needed to top up the water between antifreeze change)

 

If you have previously overheated and warped the head, or have a split gasket then it could be much les than 3 hours to 'boil'.

 

If it is a split gasket you don't always see the water leak as if it is an external leak it will normally 'boil off' on the hot engine so no puddles (you may just see a 'rusty stain;)- if it is an internal leak the most obvious indicator is emulsified oil (look at the oil on the dipstick and underneath the filler cap - is it 'milky / grey ?)

[Tony Brooks]

In that case maybe a hose has split or some other coolant leak has developed.  If it all turns out OK  remember that you need to add about 30% of antifreeze once you are sure its running properly and has no leaks. It would be worth checking the thermostat to make sure it still opens at the correct temperature.

[Bee]

Ok, If we assume the worst case scenario its still not a total disaster. If its overheated, blown a gasket, messed up a big end, run a bearing and seized all you have to do(!) is take all the ancillaries off it and take the block and all the internals to an engine reconditioner, leave it for a week or so and then go and collect a recon. short engine plus a gasket set and bolt all the bits back on again. You will probably need to examine and get the head re surfaced too. That sounds terrifying and there are things that need some experience, mostly to do with valve and fuel timing and things but think of it as a winter project and at the end of it you will have an as new (ish) engine. There are people on here that know about these engines so don't despair.

[Tony Brooks]

23 minutes ago, Bee said:

Ok, If we assume the worst case scenario its still not a total disaster. If its overheated, blown a gasket, messed up a big end, run a bearing and seized all you have to do(!) is take all the ancillaries off it and take the block and all the internals to an engine reconditioner, leave it for a week or so and then go and collect a recon. short engine plus a gasket set and bolt all the bits back on again. You will probably need to examine and get the head re surfaced too. That sounds terrifying and there are things that need some experience, mostly to do with valve and fuel timing and things but think of it as a winter project and at the end of it you will have an as new (ish) engine. There are people on here that know about these engines so don't despair.

 

Being a 1.5 the OP would also need a suitable crows foot socket so he can tighten the head down properly. otherwise it could all peahen again.

[jhodgski]

Thanks, Bee.

 

I checked the oil which is just above max... but there doesn't *seem* to be any water in it.

 

I've just topped up the water - about 3 or 4 litres this time.

 

Then tried starting her up. She turned over OK, but I noticed water is dripping out from the exhaust outlet (not from the water expansion tank rubber above it). Is this something serious?

 

(The expansion tank itself is now all burnt around the filler cap end, by the way.)

[Tony Brooks]

2 minutes ago, jhodgski said:

Thanks, Bee.

 

I checked the oil which is just above max... but there doesn't *seem* to be any water in it.

 

I've just topped up the water - about 3 or 4 litres this time.

 

Then tried starting her up. She turned over OK, but I noticed water is dripping out from the exhaust outlet (not from the water expansion tank rubber above it). Is this something serious?

 

(The expansion tank itself is now all burnt around the filler cap end, by the way.)

That shouts low water level because there would have been nothing to cool the heat transfered from the exhaust stubs that are under the manifold.

 

Have you bled the skin tank or do you have some other form of cooling system?

 

On a dry exhaust (no info on type of cooling system) there should be no water bar a little condensation in the exhaust system so that suggests both a leak into the exhaust and a rust/corrosion hole.

 

We need far more info about your system. A photo or photos would be a good start if you don't understand about wet & dry exhaust, direct raw water, indirect raw water/heat exchanger, keel cooling and skin tank systems.

 

 

 

 

[jhodgski]

It's a skin tank, but I haven't bled it. Photos to follow in a few minutes.

 

I've just started her up and loads of water pee'd out from the filler cap this time. The cap was on properly, so no idea why that happened(?)

[jhodgski]

Let me know if any more photos will help.

[Tony Brooks]

Thanks, so we can confirm skin tank cooled with a dry exhaust - typical narrowboat setup.

 

I suspect that when you bleed the skin tank you will have to put a lot more litres of water into the engine. If it all turns out OK for the next few months I would advise bleeding every day at first and then every two, three and so on days for a month or more. Thais is i ncase the head gasket is leaking and if it is gasses are likely to build up in the skin tank and reduce its effectiveness. Once properly bled no more air/gas should get into the tank for weeks.

 

As a matter of interest you skin tank looks far too fat and rather undersized for optimum cooling but I very much doubt this has anything to do with the present problem and will probably be fine for canal work. I can also see that the hot supply to the calorifier seems to have  a number of hoses Td off it. This is far from normal and I can't work out what is going on. If you had a remote engine header tank I might have an idea but there is no evidence of that. Again, unless the boat is very new to you I doubt it has much to do with your present problems.

 

I can't see much evidence of water leaking from the exhaust outlet unless you mean the one exiting the boat. If you do that could just be rain or condensation from the pipe and silencer. See if it goes away when hot. Might it be coming form the blue header tank overflow hose and running back across the engine. If so that may be normal as long as it stops when the engine is hot. If it really is from the outlet on the manifold then I think something is wrong inside the manifold, possibly a corrosion hole. The only way I know of finding out is to do a cooling system pressure test to see if the leak gets a lot worse under pressure but that needs equipment you ere unlikely to have access to.

 

 

 

[Stilllearning]

It might also have an airlock in the coolant system. Try running the engine at Rickover with the water filler cap off, and see if any big bubbles of air come out, followed by a lowering of the water level: if this happens, carefully refill, and carry on till no more bubbles appear, then refit the filler cap.

Also check the rubber gasket on the underside of the filler cap for wear, teats etc.

Good luck.

ETA

I did once see and hear a BMC 1.5 running very rough, clanking loudly, and it turned out to be a broken crankshaft, at least you don’t appear to have that problem!

Edited October 11, 2019 by Stilllearning

[jhodgski]

I tried the bleed screws on the skin tank, but just water came out so that seemed fine.

 

I also removed the thermostat and tested it: 6cm long when cold, 7cm when boiling. Not sure if that's correct, so I left it off.

 

I also took off the heat exchanger and that looks fine and doesn't seem to leak from one chamber to the other.

 

I put it all back together and topped up again and when I started the engine, all the water came splurting out of the filler cap again - and seemingly from the exhaust oulet again too (where the exhaust bolts on). It's never done anything like that before it overheated today. It seems maybe the cooling system is blocked somewhere or maybe a broken gasket could result in water being blown back like that?

 

I checked the oil filler cap this time and it does have grey sludge and water in it... :-/ So does that confirm it's the head gasket that's blown?

 

Went back just now to top her up again (another 4 litres) with the intention to make a video of where the water's coming from, but now she won't start - despite the battery having charge and the engine being fairly warm.

 

Any idea what to do next and what the associated cost might be? (Am wondering if my best/cheapest bet may be a £600 engine of ebay, which I could maybe get fitted for £400?)

[Boater Sam]

Mend it, its a head gasket failed. Better the devil you know than an unknown engine. When these engines are serviced, the head should be re torqued down to avoid this failing, frequently neglected 'cos they need the 5/8" AF crowfoot wrench to tighten the center nuts.

[Tony Brooks]

32 minutes ago, jhodgski said:

I tried the bleed screws on the skin tank, but just water came out so that seemed fine.

 

I also removed the thermostat and tested it: 6cm long when cold, 7cm when boiling. Not sure if that's correct, so I left it off.

 

I also took off the heat exchanger and that looks fine and doesn't seem to leak from one chamber to the other.

 

I put it all back together and topped up again and when I started the engine, all the water came splurting out of the filler cap again - and seemingly from the exhaust oulet again too (where the exhaust bolts on). It's never done anything like that before it overheated today. It seems maybe the cooling system is blocked somewhere or maybe a broken gasket could result in water being blown back like that?

 

I checked the oil filler cap this time and it does have grey sludge and water in it... ? So does that confirm it's the head gasket that's blown?

 

Went back just now to top her up again (another 4 litres) with the intention to make a video of where the water's coming from, but now she won't start - despite the battery having charge and the engine being fairly warm.

 

Any idea what to do next and what the associated cost might be? (Am wondering if my best/cheapest bet may be a £600 engine of ebay, which I could maybe get fitted for £400?)

 

 

1. You need a thermometer to measure the temperature at which the thermostat starts to open. Boiling it may well cause it to expel wax and fail (opeen at too high a temperature).

 

2. As far as I can see your engine does not need or use the heat exchanger core in the manifold so forget that.

 

I am with Sam now, probably a failed head gasket and also probably hydraulically locking with water in the cylinder(s).

[bizzard]

The beginning of the overheating trouble may have been a leaking water pump. Looks close up to a bulkhead but check for streaks of coolant below it, also grasp hold of its pulley and yank it about to see if there's any loose wobble on it.

[Bod]

1 hour ago, jhodgski said:

I tried the bleed screws on the skin tank, but just water came out so that seemed fine.

 

I also removed the thermostat and tested it: 6cm long when cold, 7cm when boiling. Not sure if that's correct, so I left it off.

 

I also took off the heat exchanger and that looks fine and doesn't seem to leak from one chamber to the other.

 

I put it all back together and topped up again and when I started the engine, all the water came splurting out of the filler cap again - and seemingly from the exhaust oulet again too (where the exhaust bolts on). It's never done anything like that before it overheated today. It seems maybe the cooling system is blocked somewhere or maybe a broken gasket could result in water being blown back like that?

 

I checked the oil filler cap this time and it does have grey sludge and water in it... ? So does that confirm it's the head gasket that's blown?

 

Went back just now to top her up again (another 4 litres) with the intention to make a video of where the water's coming from, but now she won't start - despite the battery having charge and the engine being fairly warm.

 

Any idea what to do next and what the associated cost might be? (Am wondering if my best/cheapest bet may be a £600 engine of ebay, which I could maybe get fitted for £400?)

"I checked the oil filler cap this time and it does have grey sludge and water in it... :"

You have water in the oil.  DO NOT run the engine.  That grey sludge has no lubrication properties.

Others who know this engine better than I, will suggest steps to be taken.

 

Bod

[jhodgski]

Tony, can you expand on what you mean by "hydraulically locking"?

 

Bizzard, I recall either hearing the odd "Tsss" noise from the engine or maybe it was like a plinking noise - my memory is so bad, can't remember which noises came from which engine!... :-/ Could either of those be the leaking water pump or something else that might need seeing to? And sorry, I didn't understand the "Looks close up to a bulkhead" part of your message - could you clarify for me?

 

Bod, thanks. OK, I'll leave it be. The nearest boatyard is only a couple of miles away, so I can drag it there.

 

I'm going to call them tomorrow for an idea of cost. Just to be sure I don't miss anything, I need to mention:

 

1. A head gasket replacement

 

2. The head to be torqued down.

 

3. A possible water pump replacement (for which I may have a spare in my previous BMC 1.5).

 

Do I also need the head skimming? And/or the bores rehoning? Or new piston rings - given that it overheated and stopped? And anything else that should be considered / looked at whilst it's being operated on?

 

NB - My previous engine also overheated, and I'm wondering now if the skin tank could be an issue. Because both engines could get hot at lower revs, I'm wondering if there is a water flow issue - maybe crud built up in the bottom of the skin tank restricting water flow??

 

Thanks for your help so far, everyone. To help prepare myself, does anyone have any idea how much a head gasket replacement would normally cost?

[bizzard]

1 hour ago, jhodgski said:

Tony, can you expand on what you mean by "hydraulically locking"?

 

Bizzard, I recall either hearing the odd "Tsss" noise from the engine or maybe it was like a plinking noise - my memory is so bad, can't remember which noises came from which engine!... ? Could either of those be the leaking water pump or something else that might need seeing to? And sorry, I didn't understand the "Looks close up to a bulkhead" part of your message - could you clarify for me?

 

Bod, thanks. OK, I'll leave it be. The nearest boatyard is only a couple of miles away, so I can drag it there.

 

I'm going to call them tomorrow for an idea of cost. Just to be sure I don't miss anything, I need to mention:

 

1. A head gasket replacement

 

2. The head to be torqued down.

 

3. A possible water pump replacement (for which I may have a spare in my previous BMC 1.5).

 

Do I also need the head skimming? And/or the bores rehoning? Or new piston rings - given that it overheated and stopped? And anything else that should be considered / looked at whilst it's being operated on?

 

NB - My previous engine also overheated, and I'm wondering now if the skin tank could be an issue. Because both engines could get hot at lower revs, I'm wondering if there is a water flow issue - maybe crud built up in the bottom of the skin tank restricting water flow??

 

Thanks for your help so far, everyone. To help prepare myself, does anyone have any idea how much a head gasket replacement would normally cost?

Look up the front of the engine which is close to the bulkhead with a torch to look for traces of leakage beneath the pump. Also grasp its pulley to see if there's any wobbly play.

If the head is removed, yes have it skimmed but it will need a thicker gasket or shim because you must maintain the original compression ratio. If yoy don't it will knock or valves will posibly hit the pistons. The bores can be checked when the heads off.  If you remove the injectors and turn the engine over on the starter and hear a clanking noise it might well be a big end run out, it might also pump water out of an injector hole which would mean either head gasket or cracked cylinder head. If you take both hoses off the skin tank and stick a hose pipe up the lower one to back flush it to see if muck comes out of the higher one. Piston rings will mean engine out to remove the sump. Have you checked the thermostat. Suspend it by a bit of string into a pot of boiling water to see if it opens.

 

 

[Tony Brooks]

A hydraulic lock is where water has got into the cylinders and as water may be considered as incompressible, unlike air, the piston just hits the water and stops so the engine won't turn over.

 

You do have a potential skin tank issue as I said, too small and too fat. For a BMC 1.5 you need, in theory, the side of the skin tank to have an area of about 8 sq ft. If my interpretation of the photos is correct (nothing to say it is) then there is also some unusual plumbing on the cooling circuit. Specifically all those Ts and small hoses on the feed from the tap back of the cylinder head to the calorifier.

[jhodgski]

Thanks. I'm going to get a boat engineer to come out and have a look at the whole setup, so will see what they recommend.

 

I've been given an estimate of £250 to repair the head gasket, by the way, which seems reasonable(?).

[bizzard]

1 hour ago, jhodgski said:

Thanks. I'm going to get a boat engineer to come out and have a look at the whole setup, so will see what they recommend.

 

I've been given an estimate of £250 to repair the head gasket, by the way, which seems reasonable(?).

It will probably need skimming, does that price include that plus new thicker gasket or shim.

[Boater Sam]

36 minutes ago, bizzard said:

It will probably need skimming, does that price include that plus new thicker gasket or shim.

Be a bit careful skimming BMC heads, the combustion chambers are supposed to protrude by a few thou and skimming makes them flush, they are extremely hard, they will only grind not with a fly cutter.

I have checked lots of heads and they rarely need skimming. I always put the gasket down with a trace of Hylomar on both sides. Its important to re torque the head nuts after initial hot run and at every other service. Buy yourself a 5/8" crowfoot wrench for your socket set.

[bizzard]

22 minutes ago, Boater Sam said:

Be a bit careful skimming BMC heads, the combustion chambers are supposed to protrude by a few thou and skimming makes them flush, they are extremely hard, they will only grind not with a fly cutter.

I have checked lots of heads and they rarely need skimming. I always put the gasket down with a trace of Hylomar on both sides. Its important to re torque the head nuts after initial hot run and at every other service. Buy yourself a 5/8" crowfoot wrench for your socket set.

Ok, then I suggest checking it with a straight accurate ground steel bar or using a large mirror with a large sheet of fine emery or production paper and rubbing the head around on it a couple of times to check flatness.