V12 Engine Problems

[Ken/Alabama]

Got 300 plus miles on the V12 in my Zephyr. Runs good and has good power. Stock engine bored .060. Changed the oil ,had 30 Weight in it during break in. Put 10-40 in it . Took it on a 500 mile round trip with no issues. On the return trip I noticed I begin to smell something like blow by coming from the engine. When I got home I raised the hood and revved the engine. Getting lots of blow by from the oil filler and smoke from the tail pipe. It's like the rings unseated, I've rebuilt many flathead V8s and a few V12s but never seen anything like this.

[texas webb]

Compression equal,plugs look good? 800 miles should be good,maybe some more run miles.

[V12Bill]

When seating rings, I drive it like I stole it. Rings seat fine. Maybe you need a little more "hard" driving on the engine.

[cdan34]

Ken, my v12 is being worked on right now and I've been thinking about how to relieve the crankcase pressure. I don't know if that is your problem. But I did have this with my last flathead v8. What I did is, create a vacuum from the exhaust with check valve pulling through a small oil separator. This takes pressure from pan and valve lifter area. I think that relieved the pressure and when I unscrew the separator I find mostly water with a slight bit of oil.
I might do this with the v12 when I start putting it together.

Good luck

Chuck

[Bored&Stroked]

Originally Posted by Ken/Alabama

Got 300 plus miles on the V12 in my Zephyr. Runs good and has good power. Stock engine bored .060. Changed the oil ,had 30 Weight in it during break in. Put 10-40 in it . Took it on a 500 mile round trip with no issues. On the return trip I noticed I begin to smell something like blow by coming from the engine. When I got home I raised the hood and revved the engine. Getting lots of blow by from the oil filler and smoke from the tail pipe. It's like the rings unseated, I've rebuilt many flathead V8s and a few V12s but never seen anything like this.

The fact that it wasn't there before - and now it is, makes me think that something has failed. Potentially a broken ring would be my guess.

I would do a compression check first -- if that doesn't show anything obvious, then I would proceed to a leakdown test.

D

[deuce_roadster]

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Since this happened after you changed oil viscosity, you might try putting the 30 wt back in and see if the problem goes away.
That really sucks on such a beautiful car. Hope you don't have to pull the engine. Any chance it is sucking oil from a defect in the intake gasket or cracked intake manifold?

[revkev6]

wasn't this a common problem with the V12 when new??

[rotorwrench]

I can't think of any reason that a change to multi-viscous oil would start a problem. I don't know much about the V12 engines but if it has any similarity to the V8 with respect to the crankcase ventilation, it should vent out the normal vent opening too. There is always some pressure that gets past the rings but it usually doesn't pressure up the crankcase to the point that is smokes from the oil fill port unless there is a broken ring letting a lot of pressure by. Smoking from the exhaust is not a good sign. I'd check the compressions as was mentioned.

Thankfully stuff generally stays together for a long time but now and then things don't. I don't second guess problems anymore as to how or why, I just get the repair done as soon as possible and chalk it up to life experience.

[hardtimes]

Originally Posted by revkev6

wasn't this a common problem with the V12 when new??

IMO, you are correct.
In fact, there is an article in one of the V12 club publications which pictured/detailed how to make the remedy (pressure vent) for this common V12 problem. Great innovative/clean piece of work also.

[Highboy34]

Check the intake manifold ports below the carb to be sure there is not a corrosion hole into the heat riser area which would allow oil to be sucked into the intake ports to the cylinders. I experienced it on my 37 Zephyr. Condensation buildup was a common problem in these engines as they had poor crankcase venting.

[cretin]

Is it stock intake? We had a situation with an aftermarket intake where it didn't have heat risers in the intake, but it also didn't block them off at the block. We didn't notice that till we had excessive smoke.