How to fix a rear crankshaft leak?

[oaries]

My 1992 1700 Xflow has developed a massive oil leak. My mechanic says it is it is most likely the rear crankshaft seal against the bellhousing. We know it is not the gearbox because any oil topped off in the engine nearly immediately finds its way to the floor (well, not quite immediately but overnight).

I am a novice with Caterhams, so I am counting on this community to advise me and my mechanic. I am in Boston (the USA one), I imported the car in the fall from Brands Hatch, and drove it about 500 mi here. it was happy motoring until now and there was barely any leak until a week ago, just a drop here and there over the winter.

My mechanic is not a Caterham expert (he focuses on vintage Alfas) but he is ready to help as long as he get his hands on the right info. So what I'd like to ascertain is:

1. What parts to order
2. How to change the seal - we hope not to have to take the engine or the trans out (but if we need to - how to).

3. To cover our bases, any other diagnostic that could produce the same big leak in that location but would not be the crankshaft seal?

4. Any tech manual you recommend beyond Peter Wallage's Kent guide.

Looking forward to your enlightened guidance (and your patience dealing with a novice long on passion but short on mechanical skills). 

Thank you - Olivier 

 

[Tazio]

Burton sell them, and I presume they'll ship  to the States

https://www.burtonpower.com/oil-seal-rear-crankshaft-fp709.html

It could possibly just be the sump rear seal, and in this kit you get the sump and crank seals and every other gasket ( except head)

https://www.burtonpower.com/cometic-full-gasket-set-less-head-711m-x-flow-fp746k.html

Ford  Motorsport in the US still make Kent blocks for Formula Ford racing, so there must be a wealth of experience in that community, so there are skills around

If you are in California, Tony Ingram, of Lotus7.com, I'm sure could help.

Alan

[elie boone]

IMHO your oil leak must be lower than the rear crank seal, i don't think that the correct oil level is that high. Maybe you have hit something with the sump especially on the rear corners. Did you inspected it from underneath to see where the oil is coming from ?

[SM25T]

Ate you sure the oil level is correct ? The right dipstick ?

[7 wonders of the world]

also look for pin holes in the sump caused by corrosion often hidden under oily layers of grime, sump gasket back in the days thee were made were very rudimentary affairs.

Sumps are often over tightened too which deforms the edge of the pan, easily fixed off the car with a toffee hammer and metal bar in a vice.

[PeterM]

Have you recently topped up the oil? If so then I'm with SM25T; as one of my theories from a lifetime in marine engineering is 'if it's mechanically OK then suddenly goes wrong, always go back to the last point of maintenance '. 

[Roger King]

I'm largely reiterating what others have said here.

To fix the crank seal you would have to separate the flywheel from the engine so this would mean engine (preferably) or gearbox out. The sump would also have to come off, along with the rear seal carrier. However, as others have said, if this is a "static" leak (i.e. it occurs when the engine is not running) the oil level should not be high enough to leak from the rear seal. The same would also apply to the sump gasket.

Are you certain that you have the correct oil level? If for some reason it is too high it is just possible that reducing it will solve the problem. If not, a pin hole in the sump might be the problem. Thoroughly degrease the bottom of the engine and put a piece of cardboard under it to see where the drip is occurring. You can also rub talcum powder on the sump to help with this, but don't leave it overnight; check it soon after starting the test.

If you do decide to go down the route of seal replacement, then yes, you would need to remove the sump and rear seal carrier and replace gaskets and seals. Do fit the sump gaskets with silicone sealant; they are notorious for leaking if fitted dry.

[Bricol]

What might be useful is if someone with a xflow could provide a measurement of where their oil level is on the dipstick, relative to the top, and possibly the height of the dip stick tube relative to where it enters the block (or some other suitable datum - top of block maybe?   Assuming both have Caterham spec sumps - assuming there is such a thing.

From accidental experience with a xflow in a Dutton trials car, too high oil level does tend to generate enormous clouds of thick white smoke out of the exhaust too

[Jonathan Kay]

Olivier: Private Message sent. Please check your mailbox.

[OldAndrewE]

Agree with all the other comments.  The best bet will be a hole of some sort on the sump unless there is far too much oil in the engine.

I don't know if the 1992 chassis is different but mine is a 1985 with a crossflow and you cannot split the engine from the bellhousing without removing the whole unit from the car.

[oaries]

Thank you all for your insights. It sounds like the first order of business is to confirm where the leak comes from.

I very lightly scraped the sump at low speed not so long ago, and your consensus seems to point to it.

I did not do any oil top-off lately; it was only after I saw oil on the floor that I checked the dipstick and noticed I was already below min; and it continued to leak after that. So while I will use PeterM's good maxim on marine maintenance again, the issue is probably not an overfill :)

How do I ascertain whether it is a static vs. running leak? Coming back from a blat last week, I immediately pushed my car in the garage and I could see a drip line over several meters on the ground, starting where I had stepped out the car. So I assume the leak happens when driving too. 

I will keep you all posted here and I'll probably have more questions after I have investigated further.  

[Roger King]

Now I think about it, there were some instances, particularly with the yellow plastic type dipstick, where the stick would fail to go through to the oil via the hole in the sump baffle and would instead end up bending and sliding along the top of the baffle. This would give  a zero reading even with a full sump.

Before you dismantle anything, I'd drain the sump and then (if the oil is reasonably new), put the correct amount back in. Then see what happens, both to the leak and the dipstick reading.

[oaries]

Thank you for the additional thoughts, Roger - much appreciated. Dipstick is all metal and it seems to slide up and down without undue friction or bending. The oil level is still at Max a few days after we top'ed it off at the shop, despite some heavy stains on the cardboard I placed on the floor - so at least not all of it is draining... I'll drive around this weekend to see what running the engine does to both the oil level and leak.
Next week (if the shop has room on the lift) we'll follow your earlier advice of cleaning the engine to re-assess where the leak comes from, in case it may be a sump crack. We'll drain it entirely and fill it at the proper level to see how it impacts the lean and dipstick. Stay tuned! Have all great weekend blats.

[Golf Juliet Tango]

Welcome to the forum Oliver.

As a Crossflow owner, I'll say that everything is fixable on them. Great engines, if dated now.