reason for loud hydraulic noise at the rear of the SRT-10 engine?

ike · Dec 25, 2012

Hello,
the SRT-10 is running well in BMW Z4 now, but there is a loud noise in the back area of the engine next to the gearbox.

The noise is very loud, sounds like hydraulic problem and ends after some seconds running on idle speed.

Does anyone know the reason of this noise?

Can it be because of higher viscosity oil?

Is it dangerous or annoying only?

Viper Specialty · Dec 25, 2012

Can you give more details?

Hot? Cold? After sitting? Sitting for how long? Better or worse when warming up? Any change when clutch is depressed and put into gear?

Were the heads off or were the lifters ever removed? History of the engine?

ike · Dec 26, 2012

Thank you for your quick reply.

The noise is hot and cold. I am not sure if better or worse when hot.
Will check this asap and try to get sound file.

The engine was not open. It is completely original except oil pan and replaced oil filter.

It was sitting for about 7 month, in a dry warehouse.

The clutch is not working correct.
It seems that there is air in the line.
We will replace hydraulic fluid next week, and hope it will work correct again.
Can we use the blue brake fluid for higher heat resistance in the clutch hydraulic?

InjectTheVenom · Dec 26, 2012

Sounds like a sticky valve lifter (please forgive the crummy translation attempt) that has an oiling problem until warmed up? Funky valve guide maybe?

roller · Dec 26, 2012

Check the throwout bearing and hydraulic clutch.

Frank

InjectTheVenom · Dec 26, 2012

Now that roller mentions it, if the gen 3 has a solid flywheel my money is on the throwout bearing that went bad as the noise persists when everything has warmed up. Either that or the friction material on the clutch plates is almost used up.

Viper Specialty · Dec 26, 2012

It sounds to me as well that it may be clutch related. It would be difficult for a lifter to remain stuck for so long if there was not water in the engine, or a pre-existing/caused problem, which does not seem to be the case. I would get the clutch fixed, and then move on from there after it can be tested.

ike · Dec 26, 2012

The noise was before the problem with the clutch appeared.

Can the oil pump cause this noise, if the oil viscosity is higher?

I presuppose that the clutch problem, is due to overheated hydraulic clutch line.
The clutch line passes near by the exhaust manifold, and maybe the heat protection was not sufficient.

Is it OK to use DOT4 blue racing brake fluid for the clutch?

together with additional heat protection it should be able to avoid further problems.

Viper Specialty · Dec 26, 2012

Higher viscosity will normally cause less noise, not more. The noise may be a problematic lifter, or even a rod bearing problem due to the engine sitting and probably not being pre-oiled. I would be cautious here.

You can use high temp fluid in the clutch such as DOT4, but in general you do not want to go with very hygroscopic racing fluids. The clutch line should never be getting that hot- fix the original problem first.

VIPER R · Dec 26, 2012

Does the noise change if you step on the clutch?

Viper Specialty · Dec 26, 2012

VIPER R said:
Does the noise change if you step on the clutch?

Clutch actuation is not working at the moment.

ike · Dec 27, 2012

The noise is not a mechanical sound. It sounds like typical hydraulic problem, like air in the steering pump or exceeded pressure in a valve.
First I thought the noise is caused by the steering pump or the hydraulic fan, but it comes definitively from the rear end of the engine.

Is the oil pump in the rear and does it have a over pressure valve, which could cause this?

Where do I find an exploded assembly drawing of engine and gearbox or could someone send it to me?

@Viper Specialty
You are right, it is not good to use the racing fluid, as it would have to be changed too often.
Will try with standard DOT4 or if not too difficult clean the system completely I will use DOT5 silicone fluid.

bluesrt · Dec 27, 2012

may be the throwout bearing, main shaft gearbox bearings, does it go away when you depress the clutch?

ike · Dec 27, 2012

bluesrt said:
may be the throwout bearing, main shaft gearbox bearings, does it go away when you depress the clutch?

I am sure that it is not a bearing.
Also the noise does not change when pressing the clutch.

reason for loud hydraulic noise at the rear of the SRT-10 engine?

ike

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