Shortened sumps and required oil levels

[Facial Hair Optional]

When I bought my Tiger I was told by the then owner that "it has a small oil leak which is quite normal for this type of engine". I discovered that it did not have an oil leak but that he had been overfilling it with oil! This was due to the fact that it has a shortened sump with a wide wing welded on (to add back lost oil volume).

I always wondered how you decided what oil level to put in if the sump had been shortened. Logic tends to make you think that you should put the same amount of oil in as before it was shortened (in other words the same amount as it says in the handbook) and that therefore the oil would register higher up the dipstick, WRONG!!!!

I recently discovered a 'new oil level' mark that someone had lightly cut onto the dipstick and that is what he had been filling with oil to. If you do this you will have oil coming into contact with the bottom of your crank and rods, you will most likely get foam, excess pressure, damage and even oil escaping from the dipstick tube (which was his oil leak!!!).

You must only fill with oil to the max level on the original dipstick no matter what. This seems counter intuitive but nonetheless it is correct! It is expalined and argued over quite well here.. http://www.rhocar.org/?showtopic=32558
Needless to say now I only fill to the original max oil level I don't get any 'oil leak' and the  car is fine!!

[Iancider]

Good point and shortened sumps really need to be baffled is serious track-day work is contemplated to stop oil starvation on corners.

Ian

[paintman]

I had the same trouble when I bought mine except in my case the dip stick was broken off....I found the bottom 1/2 of it in the sump later.

The previous owner said he put oil in till the oil pressure was about 50lb on cold!!!!!!

I got a new dip-stick (scrappy) and obviously had to cut the bottom off which resulted in it holding barely 3.5lt in the original
cut off sump.....not good, which I think contributed to the engine requiring a rebuild.

The new sump is the full length and width of the engine and fully baffled:

....and takes 4.5lt which is the minimum the engine requires according to the engine builder.

So get a new dip-stick, cut the bottom where it hits the sump and that is your level, then pour in oil till it hits the original mark and hope it has more in than min did!

    Tony

[Facial Hair Optional]

I had the same trouble when I bought mine except in my case the dip stick was broken off....I found the bottom 1/2 of it in the sump later.

The previous owner said he put oil in till the oil pressure was about 50lb on cold!!!!!!

I got a new dip-stick (scrappy)

All I can say is....  eek....  double eek....  and have you seen the price of dipsticks on ebay!!!!! I am in the wrong business!!!   

[Facial Hair Optional]

A bloke on another kit car forun put it very well, he said.....

"Oil in a sump has to do two things:

    Be high enough to be sucked up by the pick up pipe,
    Be low enough not to touch the crankshaft.

This is what the two marks are for on a dipstick.

Assuming you haven't shorted your pick up pipe (or lowed your crankshaft) these marks should remain the same."

'nuff said!

[Brandy Barrel]

Aargh mine has really been mucked up then. The previous guy has put a piece of hose on so he misses the 40's. It could be any length......
Has anyone/could some one measure their dip stick tube for me xflow 1600. Then I can work out what he has done.
Would over pressure blow our crank seals?
Maybe not a leak at all as above, it was over filling.
We just refilled the engine after the out and pressure went to 80psi!!!!

[Brandy Barrel]

I guess it should read shallow not shortened.....

[paintman]

My dip-stick has just broken off inside the sump AGAIN!!!!

That's twice now.....not counting the fact it was broken off when I bought it!!!!

[Brandy Barrel]

How is it breaking off? It must be hitting the bottom the flexing and this stress cracks the stick so maybe too long again!

[Facial Hair Optional]

I would have thought if it was hitting the bottom of the sump or anything else you would feel that as you put it in. And I doubt that would cause it to break either.

More likely it is being hit by something moving like the crank or con rod ends? Is the angle of your dipstick tube in an odd position? ie could it have been bent or moved putting the the dipstick in a position that it should not be maybe?

I've never heard of dipsticks breaking before!! Maybe try slowly putting the dipstick into the tube while the engine is running and see if it makes contact with anything as you gradually insert it?

[paintman]

I would have thought if it was hitting the bottom of the sump or anything else you would feel that as you put it in. And I doubt that would cause it to break either.

More likely it is being hit by something moving like the crank or con rod ends? Is the angle of your dipstick tube in an odd position? ie could it have been bent or moved putting the the dipstick in a position that it should not be maybe?

I've never heard of dipsticks breaking before!! Maybe try slowly putting the dipstick into the tube while the engine is running and see if it makes contact with anything as you gradually insert it?

That sounds a good idea i'll try that when I get a new one.

It did touch the bottom of the sump but I can't see that being a problem.

  Tony

[benchmark51]

If your having dipstick problems, why have one at all? Plug the dipstick tube with a removeable plug and keep your dipstick clipped in a convenient place under the bonnet. I mean a dipstick is only a dipsick at time of use, other than that it's just a plug.

[sanzomat]

Good point! Why not keep it in your tool box - save some weight!

[Facial Hair Optional]

If your having dipstick problems, why have one at all? Plug the dipstick tube with a removeable plug and keep your dipstick clipped in a convenient place under the bonnet. I mean a dipstick is only a dipsick at time of use, other than that it's just a plug.

That is a good idea but if you are even slightly OCD like I am it would bug the hell out of you that you don't know the cause!

I nearly sold a perfectly brilliant BMW once because I could not find the source of an intermittent tapping noise from the rear of the car. 2 bloody years it took me to find it, nearly had a mental breakdown!! 

If you're OCD, remove then engine from the car, get in on the bench, strip it and inspect the sump and every other part at the bottom end 'til you find the sodding cause. If you're not, then do as benchmark says!!!! 

[Facial Hair Optional]

According to my rolling road tuning guru who I spoke to today, a dipstick touching the bottom of the sump can and often will snap. Something to do with sonic vibrations causing it to fracture I think he said.

You live and learn eh?

[YellaBelly]

Good point well presented chap!

Plenty of people think that when the sump is shortened the dipstick needs to be altered. But as already said, it's all about the levels below the crank.

I found out eventually when I built the Locost, gave me a headache for ages before I had it explained to me

[Facial Hair Optional]

Thank you!

Took me a while to get my head around it too.