Crankshaft front seal oil leak

ROBBOMC

MEMBER
1999 MG MGF
1.8L
4 CYL
2WD
MANUAL
60,000 MILES

I have replaced my front crankshaft seal three times and it is leaking again. I have checked over the crankcase ventilation system and cleaned out all the vent hoses.
Seal was replaced using the rubber protector so it would not get damaged by the end of the crank.

The car does about five hundred miles each time then starts leaking again.

What else could be going wrong?

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi and thanks for using 2CarPros.

It sounds like there is excessive end play in the crankshaft. Where it bolts in the block are main and thrust bearings. Especially with a manual transmission, the thrust bearings tend to wear faster. Every time you depress the clutch, you are pushing on the crankshaft (via the flywheel). If your vehicle has a clutch switch designed to prevent starter engagement without having the clutch depressed, then the pressure is there before the oil can make it to the bearings. This causes it to wear even faster.

Since you have replaced that many seals, I feel confident that if you were to pry in and out on the crank pulley, you would see too much end play. The result, it destroys the new seal.

Let me know if you have other questions or need help.

Take care,
Joe

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Monday, November 26th, 2018 AT 6:06 PM

ROBBOMC

MEMBER
2 POSTS

So the engine has done around 14,000 miles since a complete rebuild. It is in an East/West location in a mid-engined car that has very high levels of road holding; and the driver does corner with extreme speed sometimes. Is it possible the excessive cornering speed has damaged the thrust bearing or is it more likely caused by the clutch? There is no clutch switch however the new engine was cranked with the clutch in quite a bit to diagnose gearbox related issues. The pressure plate is new, also replaced in the rebuild; and of aftermarket origin, but considered a 'standard' replacement and not a racing clutch.

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Monday, November 26th, 2018 AT 7:37 PM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Welcome back.

It is doubtful that turns had anything to do with it. I only mention the clutch because it is common that the thrust bearings wear out faster with a manual transmission. The result is excessive end play in the crankshaft. Start by checking to see if there is excessive end play in the crank.

Also, if the engine is run extremely hard, that too can cause wear to occur faster.

Feel free to ask questions or let me know if I can help.

Take care,
Joe

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Monday, November 26th, 2018 AT 7:52 PM