Thornycroft 1.8 BMC engine over heating after 15/20 mins with white smoke

[BILLYBONGO]

New problem! Started engine tonight heard a clang and stopped engine, looked and cam belt and whelk has come off. Obviously whoever put it on didn’t tighten bolt. How do I get back on without stretching belt? 

[OldGoat]

dinna fash yersel laddie, just ease the belt back over the pulley aided by a   screwdriver and not unreasonable force (a bit of lubricant - fairy liquid or soap) rotating the engine by hand at the same time.

You've go to be  very cack-handed and brutish to damage the belt - a good quality one (....) can stand quite an amount of abuse before (anyone) breaks it. It has to be done int the direction that the engine turns over.

 

As with life the first time is the worst....

Next week you'll be an expert....

[BILLYBONGO]

Legend! Thank you ??

[Tony Brooks]

1. Its not a cam belt, its the raw water pump drive belt. The reason terminology is important is because if you asked a question about a cam belt the answers you get will ave nothing to do with the actual problem.

 

2. Not quiet the pump mounting I was expecting but if you look just underneath platform the pump is mounted on it looks as if the whole thing can pivot on a single horizontal bolt with one or two locknuts. loosening some part of this bolts should allow the platform to tilt so you can get the belt on and then tension the belt.

 

I think that pump uses two ball bearings in the housing behind the pulley. Try to turn the pump by hand on the pulley. It will be a little stiff because of the friction of the rubber impeller but you should be able to turn it. If it is very stiff or even seized up then that may be why the belt jumped off. I doubt that will be the problem because it looks like a fairly new pump but who knows.

 

 

 

[BILLYBONGO]

Excellent! Sorry about the description Tony,  and yes I have just lossened the lock bolts which has as you said loosened the tension, just adjusted tension once belt was back on. All sorted! You will make a pro of me yet ????? thank you #legend ??

[john.k]

You get a couple of goes at cooling failure before the head cracks in the combustion chambers and valve seats.......if you re lucky.

[Jonan]

I have the same issue. 

The radiator cap. Or coolant tank as they call it up there. I need a replacement. But i don't know the cap pressure for it. 

The white smoke is due to the antifreezer/coolant evaporating and out. 

Just to say... the thornycroft T105 as same as the mitsubishi S4L2.?? 

I'm not sure. 

So if anyone can read for me the pressure cap of the radiator... Is it... 7 psi? Cause in mine... It got it worn out and deleted. Thanks

[Tony Brooks]

1 hour ago, Jonan said:

I have the same issue. 

The radiator cap. Or coolant tank as they call it up there. I need a replacement. But i don't know the cap pressure for it. 

The white smoke is due to the antifreezer/coolant evaporating and out. 

Just to say... the thornycroft T105 as same as the mitsubishi S4L2.?? 

I'm not sure. 

So if anyone can read for me the pressure cap of the radiator... Is it... 7 psi? Cause in mine... It got it worn out and deleted. Thanks

In canal use the pressure is probably not that critical on an engine with an all metal manifold/header tank but as you posted this under BMC and it seems you may have a Mitsubishi based engine if this were a BMC with rubber end caps on the manifold you would be ill advised to go much over a 6psi cap. No idea what that is in Kilo Pascals though.

 

The white smoke the OP referred to resolved itself as steam or burning rubber from a wet exhaust system that had no raw water injection.  You seem to be talking about coolant being ejected from the manifold and steaming. No one calls a radiator pressure cap a coolant tank although they might call the manifold/header tank the coolant tank. Before you condemn the pressure cap are you aware that if you overfill the header tank it will eject coolant as the coolant heats up and expands. The 1" below the filler neck level is often nowhere near enough expansion room on a boat with skin tank cooling. Fill header tank, get engine right up to running temperature and ignore any coolant that is expelled, leave to cool and when cold whatever level is in the tank is the correct level. If the coolant contracts so much air is drawn into the cooling system then you need to fit a remote header tank of larger capacity and change the cap on the manifold.

[BILLYBONGO]

Coolant!!? 

[Tony Brooks]

4 minutes ago, BILLYBONGO said:

Coolant!!? 

The correct strength mixture of antifreeze and water.

[BILLYBONGO]

Do I need some in my engine Tony?

[Tony Brooks]

7 minutes ago, BILLYBONGO said:

Do I need some in my engine Tony?

Are you for real or do you dwell under a bridge waiting for the billy goats gruff?

 

Sorry, but this now seems to extremely silly unless you really do have no idea whatsoever about engines etc.

[rusty69]

15 minutes ago, BILLYBONGO said:

Do I need some in my engine Tony?

Here is a great website from a guy called Tony. It explains lots of things, highly recommended reading:

 

http://www.tb-training.co.uk/15cool.htm#bmn61

 

ETA. Aircooled engines generally don't need antifreeze.

Edited March 29, 2019 by rusty69

[Jonan]

It's a petty you don't use the word radiator, as it is in the english dictionary:

Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. (from wikipedia) 

 

Maybe u just use this word for the central heating only. 

Anyway. Yes. It's the bloody cap. Rubber on the cap is worn out. 

I understood that if too much pressure... The spring gives the way to the steam out. 

And based on my experience, a very very white steam, dissipating fast. In my case from the coolant cap. 

I did buy once a wrong cap. 

So if anywank wanks to tell me the precise information... Otherwise... I continue my thornycroft mitsubishi research elsewherw. 

Cheers!! 

[bizzard]

Tain't steam its water vapour, steam's invisible.

[BILLYBONGO]

Tony thanks for your response pmsl I actually haven’t got a clue about marine engines! As it’s water cooled I thought it sucks water from the river  cools the engine then spits it back, my thinking is that coolant would pollute the river or thinking about its probably stored separately ??‍♂️?

[Tony Brooks]

OK, you do not understand it.

 

We pressurise the cooling system to raise the boiling point of the coolant. That is all. The reason for this is because in modern (say post about 1940) engines certain internal parts get very hot when the engine is working hard. These are known as hotspots and when they develop you get what is known as localised boiling of the coolant. The engine's running temperature may very well stay at normal but the steam pockets cause some coolant to be expelled. This is prevented by raising the boiling point of the coolant.

 

At typical canal   speeds and power you are exceptionally unlikely to get localised boiling so no pressure cap is required.

 

As this is in a BMC forum DIRECT raw water cooled (not heat exchanger) will suffer localised boiling and the consequential furring up and cracking of the cylinder head around the injector bosses IF it is fitted with a "normal" 80 odd degree thermostat. WE used to run our direct raw water cooled BMCs with no thermostat but a 60 degree one will probably be OK.

 

If you are saying the rubber valve seal on your pressure cap has failed then if there are no rubber ends on the manifold (as BMCs tend  to have) anything between about 6 and 15 psi will do.

[bizzard]

16 minutes ago, Jonan said:

It's a petty you don't use the word radiator, as it is in the english dictionary:

Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. (from wikipedia) 

 

Maybe u just use this word for the central heating only. 

Anyway. Yes. It's the bloody cap. Rubber on the cap is worn out. 

I understood that if too much pressure... The spring gives the way to the steam out. 

And based on my experience, a very very white steam, dissipating fast. In my case from the coolant cap. 

I did buy once a wrong cap. 

So if anywank wanks to tell me the precise information... Otherwise... I continue my thornycroft mitsubishi research elsewherw. 

Cheers!! 

Your a heat exchanger, everyone is and everything under the sun is.

[Tony Brooks]

Billybongo, my last reply was to Jonan, not you.

 

Your engine uses two water circuits for cooling. You can tell by the pressure cap on the manifold in your first photos (unless someone has done a bodge job in the past but I don't think they have.

 

If you take the pressure cap off the manifold on a COLD engine (never hot or you will get scalded by superheated steam) you should find it full to about 1" of the filler neck with water and antifreeze mixture.

 

Right through the middle of your manifold there is a bundle of brass tubes that end in the two rubber end caps and sealed by the second worm drive hose clip on the rubber ends. This is the heat exchanger core. and it sin surrounded by the antifreeze mixture.

 

It is this antifreeze mixture that is circulated through the engine by the ENGINE water pump.

 

The raw water that is sucked into the boat by the raw water (Jabsco) pump and passes through the actual brass tubes where it cools the antifreeze mixture that surrounds them.

 

So yes your engine does need to be kept full to about 1" of the filler neck with antifreeze mixture. As you do not use skin tanks the inch give or take will be enough for expansion. This should be a daily check along with whatever  strains muck from the raw water.

 

 

 

For the sake of Jonan:

 

Because our engines are basically automotive or industrial units that were designed to run  with what most people call a radiator, and indeed a few boats do use the automotive radiator, we need to differentiate between water to water heat exchangers and water to air radiators. This is called convention. Would you call a turbo inter-cooler a radiator? I think not yet it conforms to your dictionary definition. Heat exchangers on this forum have a specific meaning, as do radiators both central heating and engine cooling.

 

 

 

 

[BILLYBONGO]

Tony you sir are a legend! Thank you 

[Tony Brooks]

Billy go onto my website that Rusty69 linked to. I think that you will find much there to help you. There is a diagram of your cooling system in the mechanical course notes as there is an oil cooler. Oil coolers are the same as heat exchanger except they do oil to water heat transfer while your heat exchanger does water to water.

[Iain_S]

2 hours ago, Tony Brooks said:

(snip)

For the sake of Jonan:

 

Because our engines are basically automotive or industrial units that were designed to run  with what most people call a radiator, and indeed a few boats do use the automotive radiator, we need to differentiate between water to water heat exchangers and water to air radiators. This is called convention. Would you call a turbo inter-cooler a radiator? I think not yet it conforms to your dictionary definition. Heat exchangers on this forum have a specific meaning, as do radiators both central heating and engine cooling.

Jonan's dictionary definition contains the words "from one medium to another". Theefore, a water to water heat exchanger, or an air to air intercooler is not a radiator. It's more than convention: it's accuracy! 

[Jonan]

At least it is accurate to say that all latino speakers call it radiator. "The car's radiator" in spanish... Portuguese... Italian... 

As a curiosity fact... 

[Tony Brooks]

I would suggest that for absolute accuracy the term "radiator" should only be applied to a item where the heat is transferred by radiation, not conduction. So as all our engine cooling devices use conduction to some degree, as do central heating radiators, the dictionary definition is not accurate scientifically. However I am sure the vast majority of members knew exactly what was being talked about before Jonan decided to muddy the waters - even if he did not know.

 

As all our engine cooling devices transfer heat between two mediums via a metal they all transfer heat from one medium to another but that is no help in differentiating between radiator cooling and heat exchanger cooling. There is no way I feel I can legitimately name a heat exchanger  as a radiator because it will definitely confuse.

 

I have doubts as to Jonan's depth of knowledge if he wants heat exchanger, oil coolers, intercoolers and so on referred to as radiators. Oh and I do not give a flying fig about what "latinos" call a radiator. We all know what that is in relation to central heating or a vehicle. I do care when people try to muddy the waters and confuse. Unless his boat is one of the less than 1% that has radiator cooling his engine is cooled by either raw water (very doubtful), a heat exchange, skin tank, or keel cooler - that is unless Mitsubishi makes air cooled engines that Throneycroft marinised.

 

I don't know why he does not simply buy from someone like ASAP supplies, I bet they know the correct pressure.

[BILLYBONGO]

Will do big dog ??