Lotus Elan

How to Diagnose Failed Water Pump Bearing

PostPost by: mowog60 » Tue Jul 31, 2018 2:44 pm

A "rasping" sound emanates from under the bonnet of my 1967 Elan. It seems to come from either the generator or the water pump. Pulling and pushing the end of the two-bladed fan produces noticeable radial movement of the pump shaft, kind of a klunk-klunk back and forth. Can someone help me understand how much shaft play is too much shaft play? Has anyone traced a similar sound to a failed water pump bearing? There is no detectable coolant leakage. Thanks for the help!
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PostPost by: Concrete-crusher » Tue Jul 31, 2018 8:56 pm

Give it a few days and it will leak

Mine went the same way

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PostPost by: UAB807F » Wed Aug 01, 2018 4:27 am

Unless by some fluke the fan blades or pulley has loosened off it sounds very much like the water pump is on the way out. There shouldn't be any discernible play in the bearings if you try to move the pulley and although the mechanical seal will cope with a bit of movement for a short while it's not a long term prospect.

Mine went a couple of years ago, the engine sounded rough for a day or two while I did the "I wonder what that noise is ?" thing until I got the message with rusty water thrown about.

If it does have play/noisy bearings then I'd start planning for replacement because when it does go it'll bring the car to a halt and it's better if you're in the garage rather than out on the road somewhere.

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PostPost by: Gray » Wed Aug 01, 2018 5:29 am

A long screwdriver to your ear (or better still a mechanics stethoscope) is a very good way to identify noise sources, but I would suggest you take the fan blades off first for safety. If there is any discernible movement it's probably the water pump.
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PostPost by: alan.barker » Wed Aug 01, 2018 6:18 am

With the 2 blade metal fan on the water pump when they let go they tripan the rad and make a very nasty mess :cry: .
It happened to my car when on holiday in Scotland :shock: .
If there is play DON'T drive the car and change the pump.
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PostPost by: billwill » Wed Aug 01, 2018 10:18 am

mowog60 wrote:A "rasping" sound emanates from under the bonnet of my 1967 Elan. It seems to come from either the generator or the water pump. Pulling and pushing the end of the two-bladed fan produces noticeable radial movement of the pump shaft, kind of a klunk-klunk back and forth. Can someone help me understand how much shaft play is too much shaft play? Has anyone traced a similar sound to a failed water pump bearing? There is no detectable coolant leakage. Thanks for the help!


You should not be able to feel by hand ANY sideways movement of the water-pump pulley/fan.

Any movement indicates a collapsed bearing.
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PostPost by: mowog60 » Wed Aug 01, 2018 5:48 pm

Thanks to all for the prompt and helpful responses. The cautionary remarks are gladly received, especially Alan's comment about the radiator. Parts for the water pump rebuild will be ordered today.

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PostPost by: alan.barker » Thu Aug 02, 2018 6:28 am

Very wise man Jay.
As i said i was on holiday in Scotland (1968 +2 reg RAH 606F when the pump let go and tripaned the Rad :shock: .
I was near Glasgow and the Lotus dealer was in Edinborough "Lothian Sportscars".
I had my Tool Kit in the Boot so i removed the Cylinder Head at the side of the road and did the repair on the spot.
It ruined my Holiday and have never been back to Scotland since and that was back in about 1978.
Later on when i had a 1970 +2S i fitted an AKS module Pump and worked very well.
Maybe it could be the time to consider a "Burton Pump Module"
Alan
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PostPost by: david.g.chapman » Thu Aug 02, 2018 7:45 am

Play in the water pump bearing is never a good thing, but when I fitted a new bearing to my water pump module a couple of years ago, I found no play at all when the car was hot, and a trace of play when the car was cold.

By a trace of play I mean I can feel something when I try and rock the pulley, but I can't see anything. The water pump shows no sign of leaking. I would suggest that that situation is OK.

The water pump bearing I replaced had 0.5mm of rock, and was not leaking either. The seal inside consists of a ceramic rubbing surface backed by a spring, so it looks as if it can take a bit of play before giving up.

However, I fully understand if you adopt a zero tolerance approach (pardon the pun)!

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PostPost by: englishmaninwales » Thu Aug 02, 2018 8:57 am

+1 for the Burton pump. Not cheap, though, but is a neat, long term solution.
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PostPost by: alan.barker » Thu Aug 02, 2018 9:36 am

Well,
sitting back in your armchair with a glass of red wine it's easy to say it's ok.
But you're not the one who will be left at the side of the road saying "oh what a nuisance, my goodness what's happened" :o
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PostPost by: david.g.chapman » Thu Aug 02, 2018 10:42 am

Certainly in Mowog60's situation the water pump needs to be changed, but he was asking about how much play is too much?

If it's zero tolerance, then how long do the bearings rotate for before they show play? Are they preloaded in some way so that any play means they are toast? Any thoughts?

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PostPost by: rgh0 » Thu Aug 02, 2018 11:32 am

The bearing is a back to back dual race ball bearing. There is no significant preload and end play and axial play depends on the tolerance the balls and inner and outer races are made to.

A good quality bearing will have only a few thou of play when new. This sort of movement can be just felt as you move the shaft in the bearing housing with the housing rigidly fixed but cannot be seen and requires a dial gauge to measure. If the play gets to something you can both see with the naked eye and feel which is around 20 thou / 0.5mm then the bearing is certainly on its way out.

When buying pump rebuild kits make sure you get a name band quality bearing as lots of cheap no name bearings exist. The quality of the seals in the rebuild kits is also something to be questioned as plenty of cheap seals with poor quality components exist also but unfortunately most seals good or bad have no brand marking or packaging you can trust.

cheers
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PostPost by: david.g.chapman » Thu Aug 02, 2018 1:40 pm

Thanks Rohan - that should help us all.

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PostPost by: JJDraper » Sat Aug 11, 2018 6:45 am

How much play is too much? Difficult to answer, but Rohan's point is fair. If you can feel movement, but not see it, then I would wait before a tear down. If you can see movement, (and hear it from that location) then worry. I went through this worry over a decade ago, as I could feel movement at the pump, but not see it. The advice I was given by a well known specialist was that a 'little' play is normal. That was over 100k miles ago - no problems so far. I always thought you would see water leaks before a bearing failure. Just keep the fan belt on the edge of being too loose.

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