My 93 GTS has a healthy appetite for oil and likes to chuck out a cloud of smoke either on the over run or when you pick up the throttle immediately afterwards. I'd planned on fitting a Shark Vent as I thought this may cure it, then a friend of mine said the only way to cure this was to pull the engine and rebuild it so I cancelled the Shark Vent to put the money towards parts for the rebuild (135 000 miles on engine).

When I changed the plugs a few days ago I noticed that all four plugs on the drivers side (RHD) were fouled with oil deposits but the four on the other side were the normal light tan colour.
Before I go to all the trouble of pulling my engine does anybody have any thoughts as to why only one side of the engine would be effected. After all it's not as if the right hand side of the engine has done more miles than the left so I'd expect to see the same both sides. Could this be a crankcase venting issue, or is there something sinister causing this problem?
Any advice as awaly's would be greatly appreciated.

 

Since the stock breather is injected into the lower part of the throttle body...in theory it should spread to all cylinders equally...but you are seeing far more on only one side.....which is odd....since I also find it unlikely that the entire bank has bad valve seals or leaky headgaskets....

 

Have you thought about getting a compression test and or a cylinder leak down test before you go tearing things apart

Is the oil consumption Within spec or way out of it

 

Your friend was wrong, the shark vent will help the oil smoke problem and to a small extent the oil consumption problem. It completly eliminated the smoke problem on my 93 GTS.

Does your GTS have the full GTS breather mod or has it been de-moded? Is there a vent hose from both cam covers?

I would start by replacing all 8 spark plugs and re-check them in 1000K or so. Verify that you have a problem on only one bank of cylinders. I don't really have any ideas on why only one side.

 

Being a relatively new 928 owner I have no idea what the full GTS breather mod is, I know that the air pump system has been removed by a PO, is this what your referring to?

 

Can you post pics of the plugs?

 

I will do tomorrow, it's gone midnight here and I'm now off to bed but will do.

 

air pump has nothing to do with the oil consumption

 

Excessive oil consumption is a known issue for the GTS . The factory execuctive cars were said tp have been fitted with new replacement engines BEFORE being sold to the public. At least one GTS in G B got two new engines under warranty. When rebuilding one should drill the oil drain back holes under the oil ring.....all other 928s have holes but the GTS "holes" are blind they do not go all the way through.

 

Sorry not very good photo's but you should get some idea of the difference between the plugs on each side of the engine -

Right Side

Left side -


If not I'll try and get some better ones.

 

Hello

By all means check all of the above , but if you have a common denominator on 1 side of the engine , you need to find something that is common to the difference . Looking at the photo you need to check your camshaft timing as one side is burning well , the other is out .

Has the car had the belt changed in the recent past ?
possibility that the specs were not set correctly .

If you do not feel confident to perform this work yourself , I am sure that there are some helpers near you or a competent mechanic who is familiar with the marque .
The black set look like the the side has to much a retard in the cam timing .

Good luck .

 

Oh and I forgot to mention that you reep some perfromance benefits also .

 

I was thinking "cam timing" as well. Hard to see in those pics if the plugs are oily or just black from low combustion temperature.

If not obviously wet with oil, I'd run a compression test.

 

Thanks for the advice I'll get it checked out, is this a major job, also do you know if this would contribute to the oil consumption and smoke problem, I know GTS's are renowned for their oil consumption. I could tolerate a reduction if it saves pulling the engine right down. If the cam timing was out and it helped to reduce the consumption I would probably go with the Shark Vent and an intake refresh, rather than taking everything out and drilling pistons etc.

 

Anybody that can answer this re checking my cam timing please?