Lotus Twin Cam water pump

[vikebo]

It seems like the bearings of the water pump in my Seven needs to be replaced. After some searching and reading on the net I have a few questions.

 

Is it really necessary to remove the cylinder head to get the pump out?

 

If so, why? From what I can see on the drawings a lot of bolts on the front keep the from cover in place. On top there is one bolt on the side and two going through the head. Wouldn't I be able to remove the front cover by removing the camshaft cover, loosening the chain tensioner, and lowering the sump?

 

The backplate (behind the water pump) is kept in place by a clamp screw, do I have to remove the cylinder head to get this out?

 

Any tips?

 

Eivind

[Bare]

Yup ...head must come off! this is not well designed.

Also replace the Bicycle chain thing while you have it apart.

[neilsjuke]

you can do this repair with out removing the head but in a 7 its a engine out job you will then take the head off and do it again when the oil leaks out of the seal to the head after you have put it back together just go for it it will be quicker and you wont get bits of old seal etc going round the oil ways

[Englishmaninwales]

You will regret attempting to replace the water pump by not removing the cylinder head. You will not be able to re-assemble the timing cover with its new cork gasket and make it oil tight.

BTW I think the quality of pump bearings has alot to do with the premature failures. The original bearing on my Mk1 Lotus Cortina lasted 100k from new; the replacements each lasted about 10k, regardless of fan belt tension.

I am not familiar enough with the T/C installation in the 7 to comment on whether it is necessary to remove the engine.

malcolm

[Nigel Riches]

There was a company back in the '70s that made a replacement front timing cover, which allowed the water pump to be replaced without all the major surgery the original installation calls for, I'm sorry I can't recall the name of the outfit, but it may start you in search for more info as to whether these things still exist, would be worth getting one if you intend to keep the motor. Nigel.

 

1982. 5 speed, clamshells. B.R.G / Ali. The True Colours.

[vikebo]

Thanks for your answers.

 

I do not have the Lotus Twin Cam book, but have been talking on the phone with one who has it. He says that there is supposed to be 1/8" sling (on the older models) in all directions of the pump axel, but I am not sure what this means. I can move the axel around (up/down/left/right) about 1/8" (making a "normal" metal to metal sound when stopping), but not in/out. It's pumping water and not leaking, and there is no sound when rotated. It does not feel right and I don't want it to start leaking or stop pumping while I am driving.

 

Does anyone know how it would be to add an electical water pump on the hose and remove the belt from the normal pump to avoid loading the bearings (without removing the old pump)? I would prefer not to take the head off the engine.

 

Regarding the redesigned covers, Burton (www.burtonpower.com) has new covers so that the water pump assembly can be replaced without removing the front cover. They are priced at £175 for the front part and £110 for the back part.

 

[NickD]

You could fit an electric pump BUT you have to remove the impellor from the existing pump to stop it obstructing the water flow. To remove the impellor you have to remove the front cover... so no advantage here. Twincam water pumps are normally fairly reliable provided that an electric fan is used rather than the metal one mounted on the pump, and that the fan belt is not too tight. The pump bearings seem to suffer most from lack of use. I've run twincams in various Elans for 20+ years and never had a failure, although I've always replaced the pump when the engine is apart.

The front cover is very hard to refit without removing the head as the boss on the pump locates in a hole in the backplate and so must be slid in horizontally. This makes fitting the cork gasket between the cover and head very difficult as this is a thick gasket which is normally compressed when the head is bolted down. The only correct (leakproof) way is to remove the head and sump - sorry.