Lotus Elan

Oil Seep from Fuel Pump

PostPost by: david.g.chapman » Mon Nov 25, 2019 2:48 pm

I have been using a Burton Power First Line fuel pump in my +2 for the last few months. It works fine, but a small amount of engine oil is starting to seep from the oil drain hole on the under surface of the pump. It does not even reach the block surface under the pump.

As the pump is only a few months/2000 miles old this seems a bit premature. I think there is a basic oil seal in the pump, so it could be a normal thing that will not get any worse (perhaps the reason for the drain hole).

I cannot recall if this is par for the course for mechanical pumps - any thoughts?

Dave Chapman.
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PostPost by: JonB » Mon Nov 25, 2019 4:21 pm

I have a thought but you won't like it. Sling it and get a Huco low pressure electric pump.

Said you wouldn't like it.. but have you tried talking to Burton? Maybe it's defective?
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PostPost by: david.g.chapman » Mon Nov 25, 2019 6:58 pm

I have thought about an electric pump, but want to persist with the old mechanical design at the moment.

I have not talked to Burton about it, but they will probably offer an exchange/refund and I will then replace it. I bet though that there is always some sort of seepage through the hole, so I won't go that way just yet.

I took a similar pump apart some years ago and there was a simple rubber lip seal engaging onto the diaphragm rod. This rod goes up and down many times during the life of the pump, and it looked as if there was some side to side motion as well - not good for the seal.

Or maybe someone knows of a mechanical pump that stays oil tight for tens of thousands of miles? If anyone has a Burton pump that does not leak then I will contact Burton of course.

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PostPost by: nmauduit » Mon Nov 25, 2019 8:25 pm

I had the original style fuel pump with glass bowl before I switched to electrical (a bit reluctantly but for the promise of increased performance ;) ), and don't recall any oil seepage :
whatever lubricating fumes coming from the sump would get back there naturally (and I don't see the need for a drain hole...) are you sure the oily residue does not come from somewhere else?
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PostPost by: alan.barker » Tue Nov 26, 2019 6:53 am

Check the Breather to Cylinder Head is not blocked and also clean the Gauze inside the Metal Tube between Cylinder Head and Carbs. Block the little hole in bottom of Mechanical Fuel Pump. The little hole in the bottom of the Mechanical Fuel Pump is just to let Fuel out if Pump Diaphragm is leaking.
Is the Mechanical Fuel Pump with a glass Dome or all metal. If it's all metal many of them produce too much pressure and flood the Carbs.
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PostPost by: david.g.chapman » Tue Nov 26, 2019 8:08 am

Thanks for the replies.

Alan, I did not know about the hole in the pump being for fuel. I will have another look.

There is no gauze in the carb to head pipe, the rubber down pipe is recent and should be clear.
I run the fuel pump through a regulator set to 1.5 psi.
The First Line Burton pump is all metal.

I will give Burton a call.

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PostPost by: alan.barker » Tue Nov 26, 2019 9:29 am

Hi Dave,
the Gauze is in the metal pipe which goes from the grommet in the Cylinder Head and the Airbox. If it's blocked or needs cleaning it could cause more pressure in Crankcase. These Twinks like to breath a lot :wink: :wink:
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PostPost by: david.g.chapman » Tue Nov 26, 2019 10:10 am

Sorry Alan, I meant what you have just said. It's the pipe from the airbox, not the carbs!

I have contacted Burtons, and they should refund me if I send the pump back to them. I have ordered a different design all metal pump from SJS Sportscars and will fit that.

Here is a pic of the pump complete with leak. I will be sending this to Burtons. The rest of the pump body that you can't see is dry.

Dave.
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PostPost by: alan.barker » Tue Nov 26, 2019 10:31 am

When i fitted an all metal Fuel Pump from sjs it produced too much pressure and i had to fit a pressure regulator. It caused the Carbs to flood :shock: ( dellorto carbs).
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PostPost by: nmauduit » Tue Nov 26, 2019 11:38 am

From the photo I would go by Alanr suggestion above : the hole could be plugged temporarily, e.g.with small wood match (whether it is there to avoid depression at the rear of the membrane or to warn that leaking fuel is making its way through, possibly to the sump), but first I would investigate if there would be too much pressure in the crankcase venting through it, then why (plugged main vent, old rings letting too much blow back pass by, head gasket starting leaking then pressurizing the crankcase...)
Last edited by nmauduit on Tue Nov 26, 2019 12:56 pm, edited 1 time in total.
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PostPost by: david.g.chapman » Tue Nov 26, 2019 12:49 pm

Thanks for the additional responses.

Excessive crankcase pressure could be the cause, so I have just done a quick check. I started the engine and removed the oil dip stick. No puffing from the hole during idle or revving. I then removed the oil filler cap and put my hand over the opening. There is slight puffing at idle, but this disappears when the engine is revved.

I last measured the compression about 100 miles ago near the end of the "season", and they were 160-170psi over all cylinders. For my low compression head new pistons and rings in good bores gave a similar value when I changed them about 30000 miles ago.

So I think the engine is OK?

The rubber breather pipe was changed more recently, about 2 years/5000 miles ago. As I change the oil every 2500 miles there should not be anything to block up the pipe.

The SJ Sportscars pump will need a regulator, but as mentioned previously I always use one.

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