Moss Motors, Ltd

Hi,  I have a 1976 MGB that is consuming oil at the rate of 35 miles per quart.  I see puffs of smoke from the exhaust when accelerating or going uphill.  I installed new spark plugs for the California smog inspection (the car passed) but there is a build up on the plugs now after only 100 miles.  I did a compression check with the following results:

DRY Check: (1) 162  (2) 161  (3) 161  (4) 161

WET Check: (1) 175  (2) 174  (3) 171  (4) 165

 Do you think the problem is in the head or in the cylinders?  Any suggestions or thoughts would be appreciated.  Thanks.... 

Puffs of smoke does not sound like burning a quart per 35 miles. Neither do those compression numbers. It sounds more like BARS, the notorius British Anti-Rust System, run amok. I think it has to be leaking somewhere. Be sure to check the crankcase ventilation system but even that should cause a lot more smoke.

 

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Bayless
Never express yourself more clearly than you can think
'48 Prefect
'67 Sprite (project)

Although I'm not familar with your engine, I'd also have a look at the system that relieves your crankcase pressure.

Interested in how this turns out. Compression OK. So what is your oil pressure, low? Sure sounds like a defect in the crankcase breathing posssibly plugged? Don't know much about the pressure relief valve on the drivers side of the engine but that can or may be defective. Seems impossible to pass smog with this condition it would not in Nevada. Let me know what you find out!

Thanks for the responses.  I've been looking for leaks but haven't found any evidence of them.  I'm not familiar with the BARS and I haven't checked out the PCV so I'll check them out.  I'll let you know what I find out.  Thanks again...

BARS = British Anti-Rust System. Oil leaks sufficient to fully coat the underbody with oil so that it cannot rust.

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Bayless
Never express yourself more clearly than you can think
'48 Prefect
'67 Sprite (project)

Good one!  Yes, after looking under my B, I think it must have one!

So that brings us back to poolboy's suggestion. A too common cause if failure of the crankcase ventillation system. Like him though, I'm not familiar with your engine so can't suggest exactly where to look.

 

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Bayless
Never express yourself more clearly than you can think
'48 Prefect
'67 Sprite (project)

As the guys suggest, you must be dumping oil by the newtime! What carbs are on the car, how long have you had the car? Has somebody blocked off the vacuum lines from the carbs to the crankcase pipe?

When trying to find a splutter on my 73B last year I temporarily blocked these lines [just before the met the Y junction] using two chunks of dowling. I immediately found the source of the splutter, the rocker cover gasket was not sealing, ditto the oil-filler cap. I'd been sucking way too much air [and oil pick up] at higher revs [which coked up the plugs incidentally]. Removed dowels, fitted new gasket,and oil cap and I was back to good  CO/CO2readings at higher RPM, no splutter, and subsequently passed AirCare with flying colours. I also reduced the rust protection mechanism referred to by a considerable amount!! Hope this helps,   Cheers   - - - - -   steve

 

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To a man equipped with only a hammer, most problems look like nails

I have a 74 B that swallowed a bunch of oil one day out of the blue.

No leak showed up from the top side, but the undercarriage was well protected from rust.

In my case the flexible line from the block to the oil pressure gage line had failed at the joint at the block.  Its amazing how much oil can disappear at 50 psi or so.  So, if your B's underside is well lubricated check that flexible oil line.

Good luck.

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Bob - Safety Fast

But drive it like you stole it!

sometimes oil mileage caused by cracks in the oil tank or maybe the hose has leak. if this happens, i let my auto mechanic to check and obsreve on how to resolve this if you're looking an auto shop, you can go to 1 Stop Shop. i got this from automd. when i am searching for the California auto repair.