Hi.
I have blowby problems on my XK8.

I cleaned the breather, paying particular attension to the small breather 2.5mm hole. This made no difference.
However, Ive just repaired the heater pump, way down under the expansion tank. In the process, I snapped the brittle plastic flexi tube, about 10mm diameter. This was connected to a T piece into the throttle body, and then, I am sure, without taking too much off the car, it went to the small breather on top of the lhs cam cover.
The other end went under the expansion tank to a rigid metal pipe that seems to exit out into the front wheelarch. I will have to remove the inner wheelarch plastic cover to confirm this.
Now, the point is, that this metal pipe is blocked completely, cant blow or suck through it. When I ran the car, I disconnected the breather pipe from this metal pipe, and there was a lot of hissing, suction from the breather. After a minute or 2, the car started to run rough, so I put the pipe back on to the blocked pipe, and it ran better.
Can anyone tell me if this metal pipe that is blocked should be open, closed or partially open? I cant see the point of having it if it is closed, but if it is fully open, it seems that the car runs rough.
Ide like to investigate forarmed with as much info as possible, so any advice will be gratefully recieved.

Cheers.

Paul

 

Without knowing what year and whether left or right hand drive it's a little difficult to relate to your problem. It sounds like a early model with vacuum cruise control and you have broken one of the hard plastic tubes. You can do a patch by buying a piece of 4 mm windshield washer vacuum hose from a auto parts store and slipping it over the broken parts of the plastic tube.

 

Hi.
It is a 1998 Coupe, RHD with cruise control. I have already repaired the broken pipe, the problem is finding out if the rigid metal pipe should be blocked.


I have just taken out the inner wheel arch, and there is a load of gear bolted up in the wheelarch, just in front of the door. There are all sorts of pipework there, and read somewhere it may be the 'purge valve' or something to do with the cruise control. Anyway, Still need to find out if I should be able to blow through the pipe or not.


Paul

 

Look in the repair section sticky and find the parts list, or on Jagrepair.com. There are diagrams showing the rat's nest of plumbing for the vapor recovery system. The pipe probably belongs to that system, and you may be trying to get air through a closed valve. BTW, trying to suck through an unknown pipe is not the best idea (how do I know?).

 

Agreed, but I sucked gently at first then when nothing came out, harder and harder.


Im going to stop there , im just sounding weird now.


Paul

 

You are sounding weird...........
Try this parts diagram http://www.mediafire.com/download/nk...K8+Parts+1.pdf to see all the plumbing involved. Hopefully you'll figure it out, but if the car runs okay with the pipe/tube connection, it's probably okay. People with excessive blow-by have also had oil in the air intake tube and filter. Do you have this?

 

Hi Mike.
Youve certainly hit the nail on the head. It is in that group of 'bits', at the moment I can be no more precise than that, I will have to remove the inner wheelarch again and look further, but I have to be able to move the car about for the next week, so it will have to wait til later.


When I attempted to take out the bracket holding all the equipment, there was one rubber pipe that prevented this. I took off the clip, but as I started to take the pipe off, there was a hiss and smell of gas. I wondered then if it was part of the aircon , but couldnt quite understand why it would be connected to the engine breathing unless it was for a vacuum connection. I am not at all au fait with aircon!


I did have oil in the air filter, but have diverted the large breather hose into a catch can, and then back to the air intake, so it now drips into the can and doesnt soak the filter.


The car starts and runs so well, youde never know there was anything wrong with it.


Paul

 

There are threads concerning the baffles inside the cam covers under the breather holes, with mesh or the baffle not being in place (I've forgotten the details). You may want to do a search for them; it could be the reason for your oily filter. At least it's not something more, like blowing oil out your engine main seals, or a poorly running engine.

 

Ah, well, I do have a leaky crankshaft oil seal, although it seems to drip all the time, so more than just pressurised engine.
I have seen the baffles posts, and thats all ok. I have done just about everything I can, including 'steam cleaning' the inside of the engine, but it was a risk worth taking as it increased the compression in some of the cylinders. I know a compression test doesnt give a true state of blowby problems, but I had a theory that as it is a car that was used maybe only 1000 miles a year, that there was carbon build up, sticking piston rings.
Anyway, I will get round to doing the crankshaft oil seal, and just hope that the pressure isnt too great to blow it through again. At least its a time rather than expense fault.
I thought about changing the whole engine, but it runs so well, ill put up with the faults for now. I am taking it to the Mille Miglia in Italy in May, and ill see what occurs then. I may change the engine after that.


Paul