XJ-6 [1972] Emmision Problem

[BruceAllcorn]

On my 1972 XJ-6 (4.2 liter engine) I am having a problem with the engine smoking. There is a carbon canister to which is attached a tube from the gas tanks, a tube (or hose) running to the engine breather on the front of the engine above the water pump, and a tube (or hose) that is open to the atmosphere. There is also a hose connection that goes from the breather to both carbs. I am getting a bit of smoke exhausting from the hose that is open to the atmosphere and I also get smoke at the hose connecting to the carbs when I disconnect it from the carbs. When I remove the oil filler cap from the left cam cover there is a bit of smoke present even right after starting a cold engine. Has anyone ever experienced this problem and, if so, what is the "fix"?

 

[Deleted member 8987]

Usually that is blowby, as in rings and bore issues. Valve guides can cause it on start-up.

 

[LarryK]

TOC is right. Also, if a grade of oil less than 20/50 such as 10/40 or 10/30 can do same.

 

[BruceAllcorn]

Thanks to both TOC and LarryK for the info. I suspected something like that but since I'm not close to being an expert I prefer to defer to those, of which there are many, that know much more than me. I do use synthetic 20W/50 oil, so I suspect I'm going to have to get into the engine to solve the problem. I fugure that while doing that I will just get the whole engine rebuilt as it has been about 30 years since it has been gone in to, of which it sat for 12 years.

 

[LarryK]

Do a compression test to see If any one cylinder is a problem, then do a leak down test to pinpoint valves or rings. These engines can be revived after sitting long term if done carefully.