By Kiyoshi Hamai

Replacing a Twin Cam water pump is challenging. But, the Elan owner has the added choice of attempting a REAL challenge, changing the pump without pulling the engine. This operation is not for the faint at heart. It is absolutely easier to replace the water pump after pulling the engine, but it is possible to change the pump in car, here’s how…

1) Remove bonnet

2) drain coolant

3) remove radiator hoses

4) remove fan & fan belt

5) remove generator

6) remove radiator

7) lift car up onto jack stands so you have easy access to the sump/pan

While under there you'll note that there's a cross member just under the pan. Often PO's will have modified this cross member so that it is removeable. If so, you're in luck. If not you won't be able to completely remove the pan from the car and will only be able to gain limited access to the block.

8) drain oil (you can leave it in, but don't reuse it!)

9) turn engine by hand to TDC (remove distributor cap and note the rotor location - this is important because in all likelihood the jack shaft will turn and will screw up the timing. I always go to TDC for #1, not #4) Put the car in gear to prevent the engine from turning.

10) remove the cylinder head - loosen the chain tensioner & remove. attach a wire to the chain to prevent it from dropping into the sump. Do not turn the cams when removing the cam sprockets! Note the location of the timing marks on the sprockets relative to the top surface of the head. I usually leave the carbs & exhaust manifold on the head. Inspect the cylinders & head for condition and wear. Don't be surprised if you find a great deal of wear on the cylinder walls. If so, consider a rebuild, and pull the block.

11) remove the heater hose from the front cover

12) remove or drop the sump

13) remove the front cover & pump

Unfortunately when you remove the front cover you'll most likely loosen the back cover from the block (it's held on with one 1/4" bolt to the block). There's only a thin paper gasket that's used between the back cover/plate and the block and it can be the source of future oil leaks. I recommend removing the back cover and replacing the paper gasket. You will need to remove the jackshaft sprocket to do so.

14) replace the timing chain (do not use one with a key link!!!)

15) replace all the gaskets (you can hold them in place with a light coating of Hylomar)

16) I've always had a shop remove and install the pump in the front cover. (either Rich Kamp of Kampena or Barry Spencer of Spencer's European) Get a good pump, one with the cast impeller, not stamped metal.

This is a great time to clean the top of the block, de-carbonize the pistons. You won't be able to remove the pistons unless you have a removeable cross member, clean the head, etc. Check the cylinder walls for wear, scoring, etc. Be sure that you'll removed any large hard particles from the cylinders! Check the valves for wear, you can de-carbon the valves and head. Carb cleaner works. Check the chain guide and replace if worn. Use Loctite on the guide mounting screws.

17) install the back plate w/ new gasket. Carefully torque the mounting bolt (don't over tighten) Check that the top of the back cover is at the right height to the block deck. Now install the new chain with a wire to hold it up!

18) install the front cover (I always put a light coating of mineral oil on the O-ring. Make sure that the surface where the pump interfaces with the back cover is clean.) Check that the height matches the back cover.

19 ) install bolts and retorque according to spec.

20) install the head, pull the chain up through the head with the wire. I use long headless bolts (2) screwed in th block as guides. You'll have to wiggle around the chain guide. The reason for not mounting the pan prior to installing the head is so can fish out the chain in the event you drop it! And, believe me when I say that you'll drop it!

21) Install the sump. You'll have a challenge getting new seals & gaskets in place. The seal on the front cover can be installed with the cover is on the bench, but that's not so with the seal on the rear cover.

22) Install cam sprockets. Check valve timing. Check ignition timing (rotor position)

23) Turn engine over by hand, go 2 rotations of the crank and recheck timing.

24) Install radiator & hoses, radiator & heater

25) Install fan

26) Fill with coolant & oil

27) Cross fingers and start!!!