Oil leak onto clutch - HELP

[HazMan]

2001 FG637 with 4d33 motor.

When I bought the truck it had some issues and being ex NSW Railways it hadn't beed driven with and mechanical sympathy so gearbox was stuffed. It always dropped oil from the rear of the motor... enough to leave a good stain on driveway in a day or two.

I replaced rocker cover gasket to stop that oil leak and had a brand new gearbox/ transfer case and clutch installed and the rear main seal replaced but the oil leak persisted.

Now with 12 months on the the new clutch it is shuddering and slipping in 5th gear.

There is oil present in the rubber boot of clutch fork going into transfer case.

Questions:

1. Could new rear main seal be leaking and what can I do about it?

2. Can sump gasket leak get into bell housing and contaminate clutch?

Next trip at Christmas to High Country and I will get ANOTHER new clutch installed before then, but want to ensure oil contamination won't occur again.

Any advice greatly appreciated.

Sean

 

[SkiFreak]

It is always hard to diagnose this type of problem via the internet, but with the gearbox removed it should be pretty simple to see where the oil is coming from.
Only when you identify the source can you apply a solution.
Sorry if that sounds a bit simplistic, but I believe that this is the best approach.

 

[HazMan]

Thanks for that and I agree but as I'm paying someone to remove the gearbox and replace the clutch I would like to know what options are available.

Can you get a thicker rear main seal or sleeve the crank somehow?

Sean

 

[kerry]

Is there oil on the block above the bell housing? Is there oil on the pan between the pan and the bell housing? Can you get a small camera in the bell housing and look around? How much oil is the motor using?

 

[SkiFreak]

So Sean, do you believe that the oil leak is coming from the the engine's rear main crankshaft seal?
If so, and as you have said, you replaced that seal 12 months ago, logic would lead me to believe that the seal surface on the crack may be scored or that the seal may have been of poor quality.

Given today's technology with the manufacture of engine parts, scoring is much less likely than it was years ago, but if "crap" was allowed to get around that area it is definitely possible.
I assume that you could sleeve the end of the crank if it was badly scored, but that would not be a small job, as it would involve the removal of the crank. If you can detect some minor scoring, this can be reduced using some fine grade wet and dry paper. In a former life, as a fitter and machinist, I have repaired oil seal bearing surfaces using both methods. I should add that if the scoring is quite noticeable, sleeving or replacement is the only real option.

The other possibility is that the seal quality was not the best. Personally, I only use OEM seals and bearings when doing engine repairs these days, as I have been burnt previously using aftermarket alternatives. This does not mean that all aftermarket seals/bearings are no good, but I am no longer willing to take the risk, so I pay that bit extra and use the genuine parts. Each to their own...

 

[kerry]

Are you sure the rear main seal was replaced? Is there excessive pressure in the crankcase?

 

[HazMan]

Is there oil on the block above the bell housing? Is there oil on the pan between the pan and the bell housing? Can you get a small camera in the bell housing and look around? How much oil is the motor using?

No oil above bell housing.

Therw is oil between bottom of block and front cover of bell housing but unable to determine if it's from sump or not.

Motor uses a bit of oil... a few liters over 5000.

 

[HazMan]

Just found this when Google searching.

http://trucktechhelp.com/shop/fuso-crank-shaft-rear-oil-seal-slinger-installer/

I've never heard of this slinger thing?

 

[HazMan]

Are you sure the rear main seal was replaced? Is there excessive pressure in the crankcase?

I asked for and paid for it to be replaced....

How would I notice or measure excess pressure?

 

[HazMan]

Speedie sleeve?

http://brettstruck1.mobile034.com/p...ear-me011754-canter-fuso-guts-rear-main-.html

 

[gait]

I've always struggled with the idea of oil escaping past crankshaft rear bearing making its way round the flywheel onto the clutch. Same for oil seeping in between block and bell housing. My mental picture is that any oil that gets onto the clutch side of the flywheel gets flung off fairly rapidly.

Doesn't solve the problem, but I'd look at the clutch itself and the release mechanism.

 

[kerry]

On pressure--my 4d34 engine has a vent to atmosphere coming off the valve cover, don't know if yours does. You may see blowby coming out that vent. If you unscrew the oil fill cap you could see how much blowby it is producing. Excessive blowby with no vent will blow seals.

 

[kerry]

I've always struggled with the idea of oil escaping past crankshaft rear bearing making its way round the flywheel onto the clutch. Same for oil seeping in between block and bell housing. My mental picture is that any oil that gets onto the clutch side of the flywheel gets flung off fairly rapidly.

Doesn't solve the problem, but I'd look at the clutch itself and the release mechanism.

My thought also. My 99 FG has an adjustable rod on the slave mechanism. I'd definitely check that adjustment.