BMC 1.5 Cooling problems

[wannabefree]

Hi all.

 

I bought an old wreck last year and made it my home. I'm a boating/mechanical novice but do it myself through necessity £££. I'm trying to give the engine a new lease of life - hopefully all that remains to do with it is to sort the cooling system. It has hull mounted radiators plus a car radiator too.

 

Anyway, one of the polar end caps split and was given a temporary repair. Testing the repair, the hose that connects the water pump to the manifold/heat exchanger/header tank thing made by polar engineering split badly. It happened after I'd switched off the engine and closed the sea cock. I think that's what it's called lol. The pipe is missing from the first photo but you can see where it connects to. Incidentally I'm holding the pipe that connects to the air filter out the way with my finger:

 

Engine

 

Below is the pipe that has split:

 

Pipe

 

It split very suddenly and badly. I read a recent thread on here where someone had a problem with their coolant system over pressurising and a check of the overflow pipe was advised. Sure enough mine is blocked solid with lots of brown gunk. The little tank this pipe leads to is full of brown gunk too:

 

gunk in tank

 

So I guess I need a new little tank and pipe, plus a replacement for the pipe that has split and a new end cap. (Not the first time I've spent all day working on the boat and found that I have more to do at the end of the day then at the beginning!

 

I gather that polar engineering are no longer around and I think I can get end caps from calcutt and ejbowman but what about the pipe that split?

 

Also - what on earth is all that brown gunk?

[Ex- Member]

Hi all.

 

I bought an old wreck last year and made it my home. I'm a boating/mechanical novice but do it myself through necessity £££. I'm trying to give the engine a new lease of life - hopefully all that remains to do with it is to sort the cooling system. It has hull mounted radiators plus a car radiator too.

 

Anyway, one of the polar end caps split and was given a temporary repair. Testing the repair, the hose that connects the water pump to the manifold/heat exchanger/header tank thing made by polar engineering split badly. It happened after I'd switched off the engine and closed the sea cock. I think that's what it's called lol. The pipe is missing from the first photo but you can see where it connects to. Incidentally I'm holding the pipe that connects to the air filter out the way with my finger:

 

Engine

 

Below is the pipe that has split:

 

Pipe

 

It split very suddenly and badly. I read a recent thread on here where someone had a problem with their coolant system over pressurising and a check of the overflow pipe was advised. Sure enough mine is blocked solid with lots of brown gunk. The little tank this pipe leads to is full of brown gunk too:

 

gunk in tank

 

So I guess I need a new little tank and pipe, plus a replacement for the pipe that has split and a new end cap. (Not the first time I've spent all day working on the boat and found that I have more to do at the end of the day then at the beginning!

 

I gather that polar engineering are no longer around and I think I can get end caps from calcutt and ejbowman but what about the pipe that split?

 

Also - what on earth is all that brown gunk?

 

Brown gunk in the coolant system can be caused by gasket failure which can force engine oils into the coolant system which end up solidifying. This can happen the other way round, where water ends up in the oil. This would cause a creamy Brown sludge in your oil, noticable by taking off your oil filler cap and inspecting.

 

If the blockages aren't causing the pressuse, then again the head gasket could be leaking exhaust gasses into the coolant system causing pressurisation. Continuous water leaks are a symptom of this, fix one another appears.

Edited July 13, 2008 by Julynian

[alan_fincher]

Not sure about the sizings of your split hose.

 

ASAP supplies at

 

http://www.asap-supplies.com/

 

certainly do a 90 degree bend with a take off in much the style of yours, but sizes may not match.

 

They have protected their images, so I can't show it here, so look for....

 

Part number 206712 - HOSE 32mm90DEG + 13mmCALORIFIER OUTLET*D

 

(But beware it's a stunning £23.66 )

 

Alan

 

 

By the way I'm intrigued by your "Hull Mounted Radiators".

 

What type of boat is it, and what exactly is attached to the hull, and how ?

 

If it is cooled in this way, I'm not quite sure why you mention a "sea cock", which would normally imply pumping cold water from the cut, and ejecting heated water back into it.

 

It would be unusual to by cooling by two different methods.

 

Can you please explain ?

[wannabefree]

Thanks for the replies.

 

I've not noticed any brown sludge or mayo under the oil filler cap. Could it still be a head gasket failure but with only oil leaking into the coolant and not the other way around? Is replacing the head gasket a job beyond the abilities of a novice?

 

The engine runs fine, no smoke and "good" oil pressure.

 

Alan - thanks for the link. the boat is a 34ft narrowbeam cruiser with a steel hull and grp cabins from a dawncraft grafted on. Ctr cockpit. I haven't seen anything else like it. It looks very odd lol. Might be a one-off.

 

I don't understand the cooling system myself, but I will take lots of pictures tomorrow and perhaps you or someone else could explain it to me

 

I'd especially like to know if the sea cock arrangement makes the boat at risk of sinking! I bet it's actually something else now I've stuck my neck out.

Edited July 13, 2008 by wannabefree

[RobinJ]

I've not noticed any brown sludge or mayo under the oil filler cap. Could it still be a head gasket failure but with only oil leaking into the coolant and not the other way around? Is replacing the head gasket a job beyond the abilities of a novice?

 

The engine runs fine, no smoke and "good" oil pressure.

 

I don't understand the cooling system myself, but I will take lots of pictures tomorrow and perhaps you or someone else could explain it to me

 

I'd especially like to know if the sea cock arrangement makes the boat at risk of sinking! I bet it's actually something else now I've stuck my neck out.

I'd guess that either the engine has been submerged or left exposed to the elements somewhere?

The main cooling pipe connects from the thermostat housing on the top of the engine to the Polar heat exchanger and having travelled up and back down this the returns through the hose with an elbow to the water pump. This 'Primary' system is filled via the radiator cap on top of the Polar unit or from a header tank. Any tee on the bend is the return from the calorfier circuit which is usually taken from the rear of the block.

The Jabsco pump mounted below the engine pumps raw water through the 'Secondary' system, any gearbox or engine oil coolers fitted, then into the fonrt of the Polar heat exchanger via the end cap and out through the other and into the canal.

It is worth removing the 'tube and shell' from the heat exchanger (by removing the end caps) to clean it all out (it will be a very tight fit especially if gunked up).

It is likely that deposits and rubbish are built up on the outside of the tubes and its worth checking the tubes are clear.

This 'secondary' system is needed once the 'primary' has got up to temperature, but you will still be able to run the engine with the 'primary' for short periods.

The pipe bend back with your finger is the crankcase bretaher pipe from the tappet cover to the air intake and I always take this over the top of the Polar end cap to give it as much height asd possible and reduce oil build up in the air intake.

Raw water systems are generally reliable, provided a good quality stainless or brass skin fitting is used. There should also be either a brass filter (like a stirrup pump with two wings nuts on instead of a handle), or a plastic bowl type filter, this should be cleaned out and checked regularly with the cock off. Before putting the top back on, I always top up with water to make sure it cannot air lock. You can judge the flow by looking at the amount of water coming back out, any problems check the Jabsco impeller.

[wannabefree]

Thanks. That sounds pretty definitive to me. The engine is under boards but there's no wheelhouse or fabric cover so yes, it's likely the engine has been exposed to the elements. It hasn't been submerged to my knowledge! The boat was neglected and left stood for a long time before I bought her.

 

I'm going to give everything a good flush out, replace end caps and the required pipes, clean out the expansion tank and monitor the situation for signs of gasket failure. I'm hoping there will be no need to replace the head gasket.

 

Here are the photos I promised.

 

Overview

 

Other pump

 

Sea cock

 

Hull radiator and oil cooler for gearbox presumably

 

Other hull radiator (back view)

 

Car radiator

 

Has anyone heard of a steel hulled dawncraft before? Given that I'm building new wooden cabins I'm unsure whether to continue to call it a dawncraft at all...

[alan_fincher]

Well I hope somebody is clever enough to work out what you have, but I don't think it's going to be me.

 

The two things you describe as "hull radiators" look like "skin tanks" to me, (albeit that these don't work half as well if on the base plate of a boat, as on the sides).

 

Skin tanks are normally a closed circuit arrangement, where the water gets recirculated.

 

The usual arrangement is to connect them directly to the engine, as if they were a vehicle radiator.

 

However yours appear to be on a separately pumped circuit, with a heat exchanger between that circuit and the engine one.

 

All a bit unusual, and over-complex, but not unworkable.

 

But the killer is the "sea cock" which seems to be installed to admit canal water into the skin tank circuit. I can see absolutely no rational for taking canal water, and pumping it through the skin tank.

 

So I'm left not knowing if you are "keel" or "skin tank" cooled, (where no water should come from the cut), or "raw water" cooled, (where it does, but there should be no skin tanks).

 

Do you have water ejected out of the boat, either via the exhaust, of a different opening ?

 

I'm confused, anyway

 

Alan

[RobinJ]

I'm going to give everything a good flush out, replace end caps and the required pipes, clean out the expansion tank and monitor the situation for signs of gasket failure. I'm hoping there will be no need to replace the head gasket.

Yep, well, Humph!

I think you need to check to see how it appears to be connected?

It would appear you have:

1) Raw water inlet.

2) Two skin tanks (one either side)?

3) Car radiator.

4) Polar heat exchanger (connection on each boot?).

5) Raw water pump.

 

Remove the radiator cap on top of Polar heat exchanger, is there a sort of round brass thing underneath (shell & tube heat exchanger) it or does it drop straight into the water jacket (no heat exchanger)?

Is there definately a connection to the other end cap and does this go back into the canal?

Is the radiator run of the calorifier circuit or in circuit with the raw water or engine colling circuit?

 

We need to determine whether there is a primary/secondary system, if the raw water is just for oil coolers (and there may be two), whether it is in fact a messy raw water system.

[John Orentas]

Yes Wanna, a bit of a puzzle all this, almost as it it started life as a raw water job and someone started "improving" it.. Keep the photo's and pipe-work descriptions coming..

 

Are you sure it is not a Springer.

[alan_fincher]

Are you sure it is not a Springer.

Well,

 

It's certainly distinctly 'vee' bottomed, though I don't think Springers would typically have skin tanks down there.

 

I still think the sea cock does nothing more than feed directly into one of the skin tanks via a fairly small bore pipe, (probably only 15mm).

 

I think it may well be a raw water cooled set-up that has been converted to keel-cooled, which would explain why there are apparently still two separated circuits.

 

It sounds bizarre, but the only point I can see in the sea-cock is a way of filling the secondary circuit.

 

But I'm guessing, we do need to know if it has an outlet where canal water gets pumped out, of course.

[RLWP]

It sounds bizarre, but the only point I can see in the sea-cock is a way of filling the secondary circuit.

 

If the "secondary" circuit is completely closed, is the "sea-cock" providing somewhere for the water to expand and contract to?

 

The whole thing looks like a failed modification. The skin tank has been fitted as an alternative to raw water cooling. It wasn't big enough so the engine overheated. To avoid this the car radiator has been added. Am I reading this right? It isn't easy to piece together fromthe pictures.

 

Richard

[wannabefree]

Sorry - no time for a proper reply right now because I have to go to work.

 

I'll take a video of everything in 2 days and post a link so you can have a proper look.

 

Thanks guys.

[Ex- Member]

If the "secondary" circuit is completely closed, is the "sea-cock" providing somewhere for the water to expand and contract to?

 

The whole thing looks like a failed modification. The skin tank has been fitted as an alternative to raw water cooling. It wasn't big enough so the engine overheated. To avoid this the car radiator has been added. Am I reading this right? It isn't easy to piece together fromthe pictures.

 

Richard

 

Agreed from what I've seen too, the 2 skin tanks seem quite small, so even doubled up might not have cooled the engine sufficiently, so the rad appears as you suggest. I think this set up needs a complete overhaul even if having to add another skin tank somewhere.

 

There's clearly been overheating issues with this engine, so wouldn't rule out the possibility of head gasket failure somewhere. However the coolany system needs to be sorted first. The brown deposits described could simply be a build up of crud over the years, so gasket may well be ok.

[wannabefree]

Hello again.

 

Sorry - no video as yet but I'll put one up.

 

However, what do you think to these temperatures; do they sound reasonable?

 

ENGINE START

Fast tickover - 68 degrees (on guage) stable for 10 mins

Fast tickover in gear 79 degrees stable for 5 mins

Full throttle in gear 85 degrees with white smoke from engine evident and getting worse. Abandoned after 3 minutes. Unsure if temp would continue to rise.

Fast tickover out of gear 80 degrees stable after 5 mins -would not go down further.

ENGINE STOP

 

NB: All of this was while the boat was stationary with the bow buried in the bank.

 

 

Lots of leaking/kinked hoses have been replaced along with the radiator since we last spoke.

 

If you have a BMC and you run it at full throttle, what temp do you see? Any white smoke? And are you likely to need full throttle for an extended period of time ever?

[alan_fincher]

If you have a BMC and you run it at full throttle, what temp do you see? Any white smoke? And are you likely to need full throttle for an extended period of time ever?

We have a BMC, albeit 1800 rather than 1500, but basically the same beast

 

Ours produces masses of white "smoke" on full throttle.

 

We never have any need to run it at anything vaguely approaching full throttle - doubtfully even half throttle most of the time.

 

Even newly rebuilt BMCs seem to smoke it's part of BMC ownership, I think.

 

If a BMC has adequate cooling, you should ideally not actually see a temperature higher than the thermostat it is fitted with.

 

Originally probably fitted with 74 degrees, many now run with an 82 degree stat. It's unusual for it not to be in that range.

 

We have just swapped a 74 degree stat to an 82 degrees, and (measured with a Maplins Infra Red thermometer) 82 degrees is what we are getting. It's not rising when ushed harder, but I may opn her up through Blisworth tunnel as a bit of a test.

 

Alan

 

Current location: Cosgrove, Grand Union - just being called to help work the lock!

[wannabefree]

Hi chaps, bad news.

 

Further to this, having had the engine working well (if only occasionally) for 6 months, albeit with white smoke at startup, today after starting there was an unfamiliar noise, with the engine running very rough.

 

Lifting the hatch I could see exhaust gases escaping from the rocker cover cap. Switching off, I heard a trickle of water escaping from somewhere for a few seconds, possibly from where the filter is that extracts unburnt fuel from the exhaust gases...

 

Does this mean I have a blown head gasket?

 

Is this a total disaster? The engine was probably running for 30 seconds.

Edited January 3, 2009 by wannabefree

[LEO]

Hi,

 

Having run a similar engine for a number of years and looked at the pics of your engine I think it could have reached the stage where it desperately needs some in 'depth TLC', works which are beyond the scope of someone with only basic fitting skills.

 

Raw water cooled engines have a very limited life span and it sounds as if your engine needs a thorough 'flush through' to begin with.

 

I don't like the raw water inlet pipe looks too small and plumbed in incorrectly.

 

You could be throwing good money after bad, I would recommend seeking specialist advice and consider a reconditioned engine - correctly 'plumbed' in.

 

Leo.

[wannabefree]

Just to add because I may have been unclear, I resolved my cooling problems by giving the system a good flush, fitting a replacement radiator and replacing some of the flexible water pipes with copper pipes during the summer. Probably should have started a new thread - just wanted to give some background to my engines history.

 

I'm having an "engineer" look at the engine next week.

 

From our telephone conversation he suspects a blocked breather pipe and/or dirty injectors /contaminated fuel supply rather than a blown head gasket.

 

I was just wondering if anyone else had experience of exhaust gases exiting the rocker cover cap and what this meant. Hopefully it just means the breather pipe is blocked.

 

I'm told that recon' BMC engines are cheap as chips - if you pay about £400 for your chips that is!

[alan_fincher]

I'm told that recon' BMC engines are cheap as chips - if you pay about £400 for your chips that is!

If you can point us at anybody selling a well reconditioned BMC for any figure close to £400, I'm sure I'm not the only owner of an elderly BMC that would like the low down.

 

I think any kind of short engine that has had any reasonable amount of reconditioning done on it is likely to cost you several times that figure, unfortunately.

[David Schweizer]

Just to add because I may have been unclear, I resolved my cooling problems by giving the system a good flush, fitting a replacement radiator and replacing some of the flexible water pipes with copper pipes during the summer. Probably should have started a new thread - just wanted to give some background to my engines history.

 

I'm having an "engineer" look at the engine next week.

 

From our telephone conversation he suspects a blocked breather pipe and/or dirty injectors /contaminated fuel supply rather than a blown head gasket.

 

I was just wondering if anyone else had experience of exhaust gases exiting the rocker cover cap and what this meant. Hopefully it just means the breather pipe is blocked.

I'm told that recon' BMC engines are cheap as chips - if you pay about £400 for your chips that is!

Sorry to disillusion you, but I think you have missed a nought of that figure £4k is a more realistic figure for a fully re-built engine off the shelf, although you may get a few hundred back for the old engine. I payed just over £3k (no VAT) two years ago for my BMC 1.5 engine to be completely re-built, and that was considered by other people to have been a very good deal.

[wannabefree]

Great!

 

Well I hope I don't need one then because frankly I can't afford that.

 

Sorry to disillusion you, but I think you have missed a nought of that figure £4k is a more realistic figure for a fully re-built engine off the shelf, although you may get a few hundred back for the old engine. I payed just over £3k (no VAT) two years ago for my BMC 1.5 engine to be completely re-built, and that was considered by other people to have been a very good deal.

[wannabefree]

Despair! Had another look this morning. There's coolant in the oil - lots of it. The oil level is way way too high and the oil is not slippery it's watery.

 

God only knows what damage has been done to the moving parts (big end bearings?).

 

At this point I don't know whether the head or block is cracked or whether it is just the gasket.

 

My theory is that one of the cooling circuits might have had no anti-freeze in it and froze and expanded, cracking the head/block.

 

I added anti-freeze to the heat exchanger filler opening this Summer.

 

This is a serious setback in a boat of this value - deffinately a low point in what is supposed to be a restoration.

[raymac]

Despair! Had another look this morning. There's coolant in the oil - lots of it. The oil level is way way too high and the oil is not slippery it's watery.

 

God only knows what damage has been done to the moving parts (big end bearings?).

 

At this point I don't know whether the head or block is cracked or whether it is just the gasket.

 

My theory is that one of the cooling circuits might have had no anti-freeze in it and froze and expanded, cracking the head/block.

 

I added anti-freeze to the heat exchanger filler opening this Summer.

 

This is a serious setback in a boat of this value - deffinately a low point in what is supposed to be a restoration.

hi if you are still online now. there is a 1.5 engine and gearbox on ebay at the moment , bidding is at £350 but only a hour to go.

[wannabefree]

hi if you are still online now. there is a 1.5 engine and gearbox on ebay at the moment , bidding is at £350 but only a hour to go.

 

Hi.

 

Thank you.

 

I can afford that, but I just don't know what the right thing is to do....

[Iain_S]

I was just wondering if anyone else had experience of exhaust gases exiting the rocker cover cap and what this meant. Hopefully it just means the breather pipe is blocked.

 

There are basically three ways for exhaust gas to get to the rocker cover : up the valve stems, past the piston rings or into an oilway via head gasket or cracked head. A compression test should reveal the second two, and the first one s usually obvious if the engine is run with the rocker cover off. If the breather is blocked, the crankase will presurise and the resulting "chuffing" when the rocker cover cap is off looks a lot like exhaust, but is mainly air with a small quantity of oil smoke.

 

Are you burning oil (blue smoke in exhaust)?

 

Compression test needs done, IMO

Iain

 

Just seen post 23. Looks like gasket, at least. I'd still do a compression test before taking the head off, though. If only one cylinder is down, the rings are probably OK.

Edited January 4, 2009 by Iain_S