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Subject: Rusty manifold on a BMC 1.5

Hi Tony,

The exhaust manifold ( I think that's what it's called- it's a long rectangular block on top of the engine, with pipes coming in from each cylinder plus the cooling water in and out) on my 1972 BMC 1.5 is rusty where 4 pipes join from the engine.

Does this imply overheating? Is it anything to worry about?

Can it be re-painted? Do I need special paint?

Is it a it job to replace if it goes?

Many thanks in advance.

Mr R M

A corporate "This email must not be disclosed to anyone else" appeared here - this not acceptable to TB-Training


Dear Mr R M

I ignore the conditions you attempt to apply by the footer on your mail. If you wish to apply them please delete this email without reading the rest of it and inform me immediately. A paid for confidential service is available, the free advice is intended to help all boaters and as such questions and answers may be reproduced in any number of other media and places

As long as the exhaust manifold (yes that is what its called) is made from cast iron you have absolutely nothing to worry about..

There is a possibility that someone has fabricated it from mild steel and welded it together, so look at it and see if the edges of the "box" are welded or rounded with the same dimply texture found all over the rest of the painted surfaces. I do not think it likely, but if it is mild steel I would advise you to get a cast iron one with some urgency (probably cast aluminium nowadays) because if it rusted internally you would end up with engine damage.

Those four "pipes" duct the hot exhaust gasses (probably well over 500C) to the manifold from the cylinder head. They always get their paint burnt off as soon as the engine is put under load, so ignore it. If you feel you must paint them, wire brush off the "pipes" and apply "stove paint" (any colour as long as its black), but you really do not have to bother.

If the brighter rust you find at the start of the season worries you then spray them with any form of oil or spray grease when you lay it up, but expect clouds of smoke when the engine runs. Come to think of it, you are likely to get smoke and a burning smell if you insist on painting the "pipes".

In the unlikely event of a cast manifold failing - they normally only fail if you let the water inside freeze - it is the four nuts holding the exhaust outlet elbow onto the manifold & lift the exhaust pipe free, two nuts on each "pipe" (3 "pipes" on the exhaust manifold - the inlet manifold is a separate item, but may require removing so a new gasket can be fitted) and then undo the hoses/water joints. If its an old direct cooled engine some of the solid copper pipes have very fine threads on the unions so take great care when reassembling them.

Hope this helps

Tony Brooks


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Subject: Seized Motor


I have a 1986 Volvo Penta Inboard/Outboard Motor. The boat has been sitting not running for about 5 years. I have tried to start the motor but it is locked up tight. It was running when parked. I have tried transmission fluid and diesel oil in the cylinders on advice from friends, but cannot get the motor to turn. Is there anything that will dissolve rust and get this motor turning again? It has low hours and should fire right up if I can get it to spin again. Any advice would be greatly appreciated.

Brian D


Thank you - at last a US email that is polite and makes sense, so I will break my "delete all US email" rule and try to help.

I do not know why anyone should think diesel or transmission fluid would be very much help.

First remove the alternator drive belt because seized alternators will stop the engine turning over.

You also need to ensure that it is not the transmission that has seized. I suspect that if you can turn the prop when in neutral we could assume it is likely to be free.

Next remove the injectors (I bet its a petrol engine!! - so spark plugs) and get hold of what we call penetrating oil in the UK - "Plusgas" is a brand that sounds as if it originated in the USA). Pour plenty down each cylinder and leave it for a week, putting a little more in each day. (Its main use is freeing rusty nuts and bolts.)

Now remove the starter motor. This gives you access to the flywheel teeth. Use a very large screwdriver or other suitable lever between a tooth and one side of the starter hole to try to start moving the engine - first a little one way, and then a little the other. Use the longest lever you can, but do not snap a tooth off.

If that does not work take the thermostat housing off and ensure the block is free of water. Boil several kettles of water and pour the boiling water into the block, but the kettles back on and when boiling, drain the block again and refill with boiling water. Do this a few times until it is uncomfortable to put your hand on the block. This will expand the cylinders and may help the proceeds - go back to trying to lever the engine over.

This is likely to be a long process and even when you succeed in freeing the engine, there is still the question of the piston rings being free enough in the pistons to give compression to start the engine and to allow it to run well. I must caution you against the following, but in dire emergencies I have persuaded diesels with low compression to start by disconnecting the alternator and any other electronic equipment and then using a domestic battery to give 24 volts for starting. If you do this and burn something out its your own fault!

I fear this may end up as a strip down, but if you do free it, remember to change the oil before you have run it for long to remove all the stuff you have been putting down the cylinders - much should have drained into the sump.

Hope this helps

Tony Brooks


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Subject: Rebuild or new (and if so, what HP)



Can I pick your brains again please?

I have a 25 year old Perkins 4108 (hours unknown) in my 33ft motor sailor boat. This coupled to a TMP gearbox that is rather noisy especially at less than about 1400rpm.

The engine starts with blue smoke but this clears as soon as any load is applied and after that it runs well.

However, I intend to keep this boat and as part of a general updating programme and for peace of mind, I am thinking I may either have the 4108 reconditioned or replace it with a new engine.

I would be grateful for your thoughts on :-

a) The general pros/cons of recon or new.

You can recondition to almost as new condition. It all depends upon how much one is willing to pay and who does it and how motivated they are.

A good recon of a basically sound, known engine is likely to be more satisfactory that a new engine based on a little known base engine by an unknown mariniser.


b) My further dilemma (apart from recondition or new) which is:- I can get a new 50 hp marinised Perkins with a PRM 150 hydraulic gearbox for the same price as a Beta 37.5hp (with a PRM 120 mechanical gearbox) which of course has a similar power rating to the 4108. Whilst the new Perkins will provide more power than I will ever need it seems a good buy. However I understand that diesels thrive on hard work and I therefore I am concerned that the bigger engine would not be worked hard enough causing problems in the future.

Can you advise please: Is it better to have a big unstressed engine or a smaller relatively highly stressed engine

Am I right to be concerned or would I be able to avoid such problems with the bigger engine by for example periodically running it at full power ???.

It all depends upon the piston design, and the oil used. As you must go to sea I would have thought that you would have had ample opportunity to give almost any engine a bit of a thrash several times a year, so bore glazing should not be too likely - we could not do that inland because of the wash we would make.!

I would be basing my choice on the make and reliability of the base engine, the long-term availability of spares, the backup in your location, and the reputation of the marinised form of the engine for lack of problems. All I can say is that Beta appear to be exceptionally popular with inland boaters.

Thanks in anticipation


If your engine starts well and has good oil pressure, I would have thought that a rebore (or perhaps just a hone/glazebust of the bores) new pistons/rings, new valve guides and new bearings would give you many more years of life from your existing unit - but it all depends upon how well the job is done and the measurements that are taken.

Tony Brooks


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Subject: Kingfisher Engine Parts & Data

Hi Tony,

I have a kingfisher kd26 2 cylinder diesel engine with a blown head gasket.

Do you know where I can get a new gasket or do you know where I can get one made up using the old gasket as a pattern? Have you any information about torque settings and valve clearances?

Thanks, Mike S


Sorry Mike

This make is now virtually impossible to get spares for, so unless you have a very good reason, I feel the time for re-engining may have arrived.

The origin of the engine castings is obscure, but China has been mentioned and the company wnet through several hands before it disappeared.

Things like belts, filters, thermostats etc will probably be readily available from Motor Factors, but require patterning up if there are no part numbers on the ones you have. It is likely that you will also be able to get the pistons, rings & bearings from a Factors that specialises in these things as long as you have accurate dimensions.

I think a look at a few vintage car magazines may well show who specialises in engine parts and who makes up gaskets.

A Google on "torque to bolt diameter" will produce a number of tables that will give you some sort of guidance.

As far as valve clearances are concerned you need to seek another owner and hope they have a manual. In reality I suspect that as long as the pushrods are not aluminium setting the valve clearances to about 0.2mm would do - but do not blame me if I am wrong!

Tony Brooks


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