Coolant in sump problem

[Andygoldsmith]

Help please, I am fairly new to Lotus Elans, and the twin cam engine, although I have owned Sixties cars in one form or another for over 30 years. I purchased a Series 3 Elan about 6 months ago. The car is very original and in good condition for its age. Someone has spent a lot of time and money on it in the past. There is only 39k on the clock and it had been in dry store for the best part of 20 years before i purchased it. The engine was running roughly when viewed it but it didn't appear to need more than a tune up. However when I got it home it became obvious that coolant was getting into the sump because there was significant water vapour coming out the engine breather and the sump level had risen. I checked whether any water was getting into the cylinders, these were dry.

So I took the head off to investigate further. The head gasket was quite new but intact, although there was some marking of the gasket surface which suggested that water may have been finding its way into the oil ways. It didn't appear to have been coated with the correct gasket sealant. I thoroughly checked the head and the block - both have completely flat surfaces and there is no corrosion damage. In fact it looks like the engine has recently been rebuilt and therefore in good condition.

Cutting a long story short I bolted the head back on, new gasket and bolts, correct type of sealant and torque settings and tuned up the engine so that it was running sweetly. However the same original problem is evident, water in the sump and vapour at the breather when engine is hot. In fact I left the coolant system full and depressurised (cap off) whilst we went away on holiday for a couple of weeks and over this period the content of the cooling system ended up in the sump. There are no external water leaks and the water pump runs fine no bearing play and no rough running.

The only thing i can think of is that the seal on the water pump is defective and that this could be causing the problem so i am now looking at replacing the water pump but before I do this, has anyone got any ideas on my diagnosis or whether there are things that I need to look at first to confirm that I haven't got a leak elsewhere that I might have overlooked. Any comments or views would be appreciated.

Thanks

Andy

[rgh0]

Hi Andy
How much of the water ended up in the sump when you left the car. The level the engine block drained down to will be the point where he leak is if you can identify this.

It could be many possible locations
e.g from top to bottom
a cracked head
a failed head gasket
a leaking water pump / front cover assembly ( through the O rings possibly)
a cracked block

If you cant track down the specific source of the leak it will be a longer process and pressure testing each component and then doing a very careful rebuild once you fix the leak source

good luck, its all fixable!
Rohan

[Andygoldsmith]

Don't know exactly how much water s in the sump but at a guess it was in the region of half a gallon - which suggests a leak lower down the engine, such as the water pump.

[rgh0]

pull the head off without draining the coolant and see how far down the block the water has gone if possible.

cheers
Rohan

[Tonyw]

Andy,

I had the same problem as you some time ago. I ended up taking off the rocker cover and pressurised the cooling system, I saw water leaking past the water pump O ring seal. When I took it all apart I found the O ring was a few thou smaller in diameter than the replacement I bought from the Elan Factory, I put a new O ring in and this fixed the problem.

It was not difficult to see the leak but I had look in the right area and as I was just testin it I used plain water it might have been better to us coolant as this has a colour.

Hope this helps.

Tonyw

[Andygoldsmith]

Thanks for all the advice, Today I rigged up a 10psi air supply to the coolant system with the cam cover off and with a listening tube it was easy to hear that the water pump has a significant leak, somewhere around 1 o'clock position on the pump housing if you are looking from the front of the engine. So it's a pump out job now. Next question is do I replace the pump or just the seals? Or is it do I go for a replaceable pump set up or stick with the original design?

Andy

[rgh0]

Pull it apart and have a look at the cause of the leak. If the casing and O ring carrier assembly is badly corroded then you will have to go for a new front cover and pump. If they are in good condition and just need a clean-up and reassembly with new seals then going to a new removable cartridge style is a personal choice based on ease of long term maintenance.

cheers
Rohan

[billwill]

Thanks for all the advice, Today I rigged up a 10psi air supply to the coolant system with the cam cover off and with a listening tube it was easy to hear that the water pump has a significant leak, somewhere around 1 o'clock position on the pump housing if you are looking from the front of the engine. So it's a pump out job now. Next question is do I replace the pump or just the seals? Or is it do I go for a replaceable pump set up or stick with the original design?

Andy

Worth doing if you plan to keep and use the car yourself, but you will probably blanche at the cost of a pump module conversion. It needs the module plus the front and back of the timing case. On the other hand a pump repair kit plus a new adaptor ring (the bit the O-rings go into) is relatively in expensive.

http://www.burtonpower.com/catalogsearc ... water+pump

http://www.burtonpower.com/water-pump-a ... fl845.html



http://www.burtonpower.com/water-pump-h ... -assy.html
http://www.burtonpower.com/back-plate-f ... fl843.html
http://www.burtonpower.com/water-pump-r ... l304k.html
http://www.burtonpower.com/front-cover- ... fl844.html

[tcsoar]

Hi Andy,

I had this problem earlier in the year and as I anticipate keeping the car, only just back on the road this year after 24 years, I went down the new pump module from Burtons. Not the cheapest option but it is a lovely piece of kit and straight forward to install.

Chris.

[Andygoldsmith]

Arrow point towards coolant bypass channel, point where I believe leak was.

I have got the front housing with the water pump out of the car. Close inspection of the pump and housing tells me that the pump bearing and seal are good. the o ring seal that is visible (the pump cartridge is still in the cover at the moment) is intact and appears to be free of damage. So I dont think the water was leaking from this o ring, there was too great a flow for it to be possible. However there are a couple of things that I am not sure of that i wonder if anyone can provide an answer to.

firstly there is a fourth hole in the housing in the land of metal surrounding the pump impeller. checking with a thin piece of wire, it is obvious that this hole forms part of a coolant passageway which runs from the head to the suction side of the pump impeller. My guess is that it's an engineered bypass to allow coolant flow and prevent local overheating till the main thermostat opens. This hole happens to correspond with the point that I was able to detect air escaping when I pressure tested the cooling system and its now clear to me that the point of leakage is from this bypass - there is almost certainly an ineffective seal between the two mating faces , ie between the backplate and the front cover, in this vicinity. The interesting thing was that there was no gasket in place to seal this mating face. should there be? How is a seal achieved if a gasket is not used, should a particular type of sealant be used.

Secondly the cam chain rub strip which is attached to the left side of the cover (looking from inside) is about 20 thou proud of the cover mating flange, which is immediately next to it. the tapped threads for the mounting screws are at fault, they are not in the correct place and force the rub strip into a proud position when the screws are tightened. My question is should the metal backing plate of the rub strip lie flush with the surface of the flange and could it feasibly cause the cover to sit proud of the flange if the strip isn't flush. I ask because there is about 15 thou distortion on the cover when you put a straight edge across the flanges, with metal surrounding the water pump sitting proud. - this is most evident at the top coincident with the position where the leakage was from.

Thanks for all the feedback on original vs cartridge pump, I am starting to lean towards forking out for a Burton kit but would really like to understand exactly why coolant is leaking from the water pump area before i commit to the outlay

[billwill]

The guide strip for the timing chain does overlap the front cover of the timing case a bit. I'm not sure how much, from memory. It's not normally a problem.

I just use thin layer of silicone instant gasket on the mating surfaces of the halves of the timing case.

[tcsoar]

Andy,

When mine started to leak I found it by filling up the cooling system and without any external pressure I could see water welling up in dip in the casting just above and to the right of the bypass arrowed in your picture, it would collect there until overflowed and run down into the sump then start to fill again.
The pump and seals had all been replaced during the engine re-build that I did myself. Initially the engine run without a problem but I decided to replace the 7lb radiator cap with a 10lb one and then took it in a bit of a run, water pump then started leaking. Considered all the options and decided to stop relying on 40+ year old parts, and I didn't want to take the engine out again just to do the pump.

Chris.

[rgh0]

The front cover to back plate was sealed by "apply a suitable jointing compound" according to the workshop manual section E22 paragraph 5. This "suitable jointing compound" was probably something like hylomar back in the 60's. I use Loctite anaerobic gasket forming compound these days around both the pump area including this recirculation passage and around the outer rim of the front cover.

It looks like your problem was that when this was assembled they left off the sealant.

cheers
Rohan

[billwill]

I'm not sure how you can see with the impellor in place that the waterpump rotating seal is in good condition. If the previous owner took off the front cover for suspected pump failure, it may be that they replaced the water pump or they may have just popped the front cover back on (without sealant) to sell the car.

If you contemplate using the original pump & timing case, you should seriously consider pressing the pump bearing out from the front (see details that I recently posted on another topic) to inspect or replace the pump. You won't really want to go to the hassle of reassembling it as is and then discovering a drip, drip, drip or squirt of coolant from the tiny drain hole on the pump boss at the front.

By the way make sure that drain hole is clear, it is your signal from the engine that the pump seal has failed.

See this and following messages, in fact read the whole topic, though it relates to the AKS module a lot of the discussion can be applied to the standard Lotus pump and to the Burton Modular one.

lotus-twincam-f39/aks-water-pump-module-strip-t28923-45.html#p195426