My 365GT2+2's smoking habit

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sjvalin
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My 365GT2+2's smoking habit

Post by sjvalin »

I'd like to get to the bottom of why my Queen smokes a bit as I plan to put it up for sale, and if there is a straightforward and cost effective fix, I'd like to get it done.

The car has less than 40K miles on it. About 6K miles ago, the previous owner replaced all the valves as the stem ends weren't properly hardened from the factory, and were worn and couldn't be adjusted properly. At that time, the engine did not smoke. I bought it about 4K miles ago, and it was smoking a little from the #2 pipe (when looking from the rear). It has gotten progressively worse.

I am expecting a problem with cylinders 10, 11, and/or 12, based on the exhaust pipe that is smoking. Last weekend, I took all the driver's side spark plugs out to compare them, and they all look uniformly tan. None of the plugs were black or oily to indiciate which cylinder is burning oil.

Here are the plugs, in order from 12 to 7:

Image

Here's a close-up of 12, 11, and 10:

Image

Santa brought me a leakdown gauge for xmas, so I did a leakdown test on these 6 cylinders. 12, 10, 9, 8, and 7 all have a remarkable 2% to 2.5% leakage. #11 has this, too, for part of the piston travel! Somewhere near TDC, the leakage increases to ~18%!

What does this all mean? I DON'T KNOW - which is why I"m asking here! To me, it seems like #11 rings are ok since it can get a good seal for part of the stroke, so maybe there's carbon built up on the cylinder walls? If oil was getting past the rings, wouldn't the #11 spark plug be black?

So how does oil burn but not get on the plug? My speculation has always been that a stem seal has failed, which is plausible given the crap in today's gas. If an exhaust stem seal has failed, wouldn't oil possibly drip down the stem to the exhaust valve, and then burn on the way out the exhaust without even getting into the combustion chamber?

Any thoughts or things to try? Are there any treatments to fix the #11 issue? By the way, the car runs fantastic and I hate to sell it, but I've got too many cars that I don't pay enough attention to. My Daytona may be next. :-(

-steve
1968 365GT2+2 11649 ; 1971 365GTB/4 14201 ; 1985 308GTS QV 56585
afwrench
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Re: My 365GT2+2's smoking habit

Post by afwrench »

Hi Steve, first things first. Are you sure it is oil smoke? Mike
72,365gtc4,14681,2007 599 GTB
sjvalin
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Re: My 365GT2+2's smoking habit

Post by sjvalin »

Yup - I'm sure it's oil. It certainly smells like oil!

-steve
1968 365GT2+2 11649 ; 1971 365GTB/4 14201 ; 1985 308GTS QV 56585
330Jim
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Re: My 365GT2+2's smoking habit

Post by 330Jim »

A leak down tester is not the best tool for checking for an oil smoking issue. It will give you a good indication of the piston ring seal and how well the valve seats and head gasket seals but it will not tell you anything about the valve guide seals. Under what conditions does it smoke? Smoke on start up indicates, a valve guide or valve seal issue. So does a puff of smoke when you shift. Smoke under hard acceleration is a piston ring issue. Blue smoke is oil, white smoke can be brake fluid (from the brake booster), coolant and just plain condensation.

I am a little curious how you did a leak down test, normally if the piston is more than a couple of degrees from TDC it will quicky rotate the engine so the piston is at BDC. It sounds like you were checking the leakage at several crank angles as the piston approaches TDC.

If you have a smoking issue at start up you will see a pool of oil on the closed valves if you let it sit overnight. I have used a boroscope down the carb to look at each of the valves in the past. It is suprising how much oil is on the valve when the valve guides are worn out.

Note, unless the smoking is really bad there is a chance that the traces of it will burn off on a run. I think your best chance of seeing it on a spark plug is to cut the engine while it is smoking and pull the plugs right away. Of the photos you have presented, #10 looks the most likely to have an oil consumption issue to me. However it is difficult to tell for sure in the photo, if it is the cylinder, then I would expect the smoking issue to be pretty minimal.

Cheers Jim
sjvalin
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Re: My 365GT2+2's smoking habit

Post by sjvalin »

Thanks, Jim, for the reply.

I started off with a leak down test to be sure there wasn't something obviously wrong. I didn't have the valve cover off, so I couldn't see exactly TDC. I was looking at the distributor to figure out which cylinder was on the compression stroke. I moved the engine with the car in 4th gear and took a few readings. You are right, adding compressed air wants to push the piston down! I held the car with my foot under the tire! I had to relieve the pressure in order to move the car. I couldn't see any other way of turning the engine.

Regarding the smoking - it happens at all times - cold, hot, idle, accel, decel. It's pretty constant. I"m not sure a plug cut would help since it is always smoking. I'd likely get the same results. Maybe it's not bad enough to leave residue on the plugs. It is bad enough to have good samaritans point out that my car is smoking. :-) If oil was dripping down an exhaust valve stem, would you expect to see residue on the plugs? I'm not sure I can see how the oil from an exhaust valve would get drawn into the combustion chamber.

It could very well be the guides. Since it went from not smoking, to smoking in under 5K miles, it doesn't seem like the guides would wear that quickly, which is why I think it may be the stem seals.

Do you have any comments on the unusual leakdown readings for cylinder 11?

Thanks!

-steve
1968 365GT2+2 11649 ; 1971 365GTB/4 14201 ; 1985 308GTS QV 56585
Michael Greenspan
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Re: My 365GT2+2's smoking habit

Post by Michael Greenspan »

At the risk of appearing realllly dumb, I would ask if it is possible that you have overfilled the oil sump. I did that inadvertantly thinking I was down a quart of oil and wound up having smoke appear constantly, in an engine that had been rebuilt and did not smoke. I am practicing what my business partner would always do - ask the dumbest question, just in case.

I thought by driving a lot I would burn the oil off, but it wasn't really having much of an effect.

When I finally drew the oil back down to the right level it took a little while but the smoke was gone.

Michael
sjvalin
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Re: My 365GT2+2's smoking habit

Post by sjvalin »

Michael,

nothing is dumb when it comes to these cars! If anything, I probably need to add some oil, so I know I haven't overfilled it. That is assuming my dip stick is accurate!

-steve
Michael Greenspan wrote:At the risk of appearing realllly dumb, I would ask if it is possible that you have overfilled the oil sump. I did that inadvertantly thinking I was down a quart of oil and wound up having smoke appear constantly, in an engine that had been rebuilt and did not smoke. I am practicing what my business partner would always do - ask the dumbest question, just in case.

I thought by driving a lot I would burn the oil off, but it wasn't really having much of an effect.

When I finally drew the oil back down to the right level it took a little while but the smoke was gone.

Michael
1968 365GT2+2 11649 ; 1971 365GTB/4 14201 ; 1985 308GTS QV 56585
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tyang
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Re: My 365GT2+2's smoking habit

Post by tyang »

sjvalin wrote:Thanks, Jim, for the reply.

I started off with a leak down test to be sure there wasn't something obviously wrong. I didn't have the valve cover off, so I couldn't see exactly TDC. I was looking at the distributor to figure out which cylinder was on the compression stroke. I moved the engine with the car in 4th gear and took a few readings. You are right, adding compressed air wants to push the piston down! I held the car with my foot under the tire! I had to relieve the pressure in order to move the car. I couldn't see any other way of turning the engine.

Regarding the smoking - it happens at all times - cold, hot, idle, accel, decel. It's pretty constant. I"m not sure a plug cut would help since it is always smoking. I'd likely get the same results. Maybe it's not bad enough to leave residue on the plugs. It is bad enough to have good samaritans point out that my car is smoking. :-) If oil was dripping down an exhaust valve stem, would you expect to see residue on the plugs? I'm not sure I can see how the oil from an exhaust valve would get drawn into the combustion chamber.

It could very well be the guides. Since it went from not smoking, to smoking in under 5K miles, it doesn't seem like the guides would wear that quickly, which is why I think it may be the stem seals.

Do you have any comments on the unusual leakdown readings for cylinder 11?

Thanks!

-steve
Hi Steve,

Your plugs look relatively clean for the oil burning you describe. Perhaps oil is getting on the valve and being pushed out with the exhaust. I'm not sure. I don't know how much of the valve stem seal you'll be able to see when you remove the valve covers. It's pretty buried under the keeper and springs.

The anomaly in the compression numbers on #11 should be checked to see if the overall compression of that cylinder. If the compression numbers match the other cylinders, I would run the leak down again to double check your work.

Tom
'63 330 America #5053
330Jim
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Re: My 365GT2+2's smoking habit

Post by 330Jim »

I agree with your point of checking the health of hte engine by doing a leakdown test.

I also agree with Tom, I would do a compression test and see if #11 has any issues. If the compression is good I would keep running it. If there are some issues, I would try the leakdown test again to see if you can pinpoint were it is coming from. If you have access to a boroscope it may also be worth a look in the cylinder to see how the bores look on #11.

I am starting to think it is an exhaust guide issue too. Note the exhaust is plenty hot enough to cause it to smoke (yet the speark plug would still be clean). If you want to check just put a drop of oil on the exhaust manifold and see how much it smokes. The best way I can think of to narrow down the cylinder that is causing the issue is to pull the exhaust manifold. If the guide is leaking I would expect that port to be black and possibly wet with oil versus a dark grey/spark plug color for a good cylinder.

Before I pulled the exhaust though I would recommend checking the PCV if your car has one. I would simply disconnect it and see if the smoke goes away. Based on your spark plugs it seems unlikely this is the issue, but I always like to check the easy things first.

Cheers Jim
sjvalin
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Re: My 365GT2+2's smoking habit

Post by sjvalin »

Thanks, everyone, for your thoughts. I'll first try a compression test (I thought of it after I had put all the plugs back in!) to see what #11 is doing. I'll then likely take the valve covers off, and possibly the rocker assembly, and see what shape the stem seals are in. I guess it could be the guides, too, but the problem has come on fairly quickly and I would think it would take many more miles for a smoking problem to develop from the guides. Short of pulling the head, are there any tricks to determining if it's the guides?

Oh, and while I'm here, can anyone recommend a decent, cost effective, spring compressing tool for these heads?

-steve
1968 365GT2+2 11649 ; 1971 365GTB/4 14201 ; 1985 308GTS QV 56585
8339
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Re: My 365GT2+2's smoking habit

Post by 8339 »

Steve, reluctanly I'm going to jump in here. Two things to consider, first what kind of oil are you using? I have a few customers with vintage Ferraris that use synthetic oil for no other reason than it smokes less, my self included. These are vintage Ferraris with decent compression and leak down. Just a thought and an inexpensive method to see if it changes anything.

Second issue, on your 365 you have postive crankcase ventilation control. In years past I have seen many, and I do mean many cars that smoke like a freight train only to find out the flame arrester in the valve cover is completely clogged and now the crankcase ventilation is being sucked into intake in a heavy manner. In fact in my Toyota days, dealers would rebuild Tercel motors due to excess smoke only to find the engine still smoked after the rebuild. I would go to the dealer as the factory rep, only to weigh the old valve cover versus the a new valve cover, low and behold the old cover weighed twice as much due to the build up residue in the flame arrester in the cover. On your 365 there is less crankcase breathing than the earlier cars with dual oil fill caps and draft tubes. I believe on your car you have two outlets on your left valve cover that has a hose that goes to air cleaner and one that goes to the intake manifold. One of the outlets may a have a tee that goes to the back two intake manifolds. If either of those hoses don't have sufficient air flow you may have your smoking gun, no pun intended. I'm assuming inside the outlet on the valve cover there has to be either a chamber or some kind of brass or bronze wool to break up any flame front from entering the crankcase. If the that's clogged it needs to be cleaned. By the way without a flame arrester if there is a back fire it's possible to blow apart the oil pan, i've also seen that more than once. These are just suggestions and observations before you go and spend a lot of money.

Richard Garre
Radcliffe Motorcar Company
sjvalin
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Re: My 365GT2+2's smoking habit

Post by sjvalin »

Richard,

Thanks for the response. I've tried both Castrol 20/50 and Swepco 20/50. I believe Swepco is in there now. I don't use synth on old cars that weren't designed for it.

My Queen is a Euro model. I'll see what sort of PCV system is on it, but I don't recall seeing any hoses or valves to the valve covers. I would also think it would smoke equally through all the pipes, but I am only smoking through one of the 4 pipes (corresponding to cyl 10, 11, and 12).

Thanks again!
-steve
1968 365GT2+2 11649 ; 1971 365GTB/4 14201 ; 1985 308GTS QV 56585
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tyang
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Re: My 365GT2+2's smoking habit

Post by tyang »

sjvalin wrote:Thanks, everyone, for your thoughts. I'll first try a compression test (I thought of it after I had put all the plugs back in!) to see what #11 is doing. I'll then likely take the valve covers off, and possibly the rocker assembly, and see what shape the stem seals are in. I guess it could be the guides, too, but the problem has come on fairly quickly and I would think it would take many more miles for a smoking problem to develop from the guides. Short of pulling the head, are there any tricks to determining if it's the guides?

Oh, and while I'm here, can anyone recommend a decent, cost effective, spring compressing tool for these heads?

-steve
Hi Steve,

You could put compressed air into the cylinder to hold the valve shut, remove the keeper and spring, and wiggle the valve to see if there is play in the guide. Instead of using compressed air, you can also uses a length of rope stuck down the spark plug hole to hold the valve in place as well.

We use a regular c-shaped valve compression tool with a couple custom spacers to hold the spring in place, but it only works with the head removed.

Doing easy thing first, I would try to see if it's the valve stem seals.

Good luck.

Tom
'63 330 America #5053
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Bryan P
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Re: My 365GT2+2's smoking habit

Post by Bryan P »

8339 wrote:Second issue, on your 365 you have postive crankcase ventilation control. In years past I have seen many, and I do mean many cars that smoke like a freight train only to find out the flame arrester in the valve cover is completely clogged and now the crankcase ventilation is being sucked into intake in a heavy manner. In fact in my Toyota days, dealers would rebuild Tercel motors due to excess smoke only to find the engine still smoked after the rebuild. I would go to the dealer as the factory rep, only to weigh the old valve cover versus the a new valve cover, low and behold the old cover weighed twice as much due to the build up residue in the flame arrester in the cover. On your 365 there is less crankcase breathing than the earlier cars with dual oil fill caps and draft tubes. I believe on your car you have two outlets on your left valve cover that has a hose that goes to air cleaner and one that goes to the intake manifold. One of the outlets may a have a tee that goes to the back two intake manifolds. If either of those hoses don't have sufficient air flow you may have your smoking gun, no pun intended. I'm assuming inside the outlet on the valve cover there has to be either a chamber or some kind of brass or bronze wool to break up any flame front from entering the crankcase. If the that's clogged it needs to be cleaned. By the way without a flame arrester if there is a back fire it's possible to blow apart the oil pan, i've also seen that more than once. These are just suggestions and observations before you go and spend a lot of money.

Richard Garre
Radcliffe Motorcar Company
Richard is correct - and I have attempted to attach the spare parts page to show the system.
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1968 365 GT 2+2
s/n 11199
1955 s.II 500 Mondial
s/n 0556(0446)MD
1965 Alfa Romeo Giulia Sprint Speciale
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