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Suddenly blue smoke while idling

Joeneke

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Hi everyone... Last week I brought my '72 3.0CS to a specialist for a tune up of the carburators and a general engine adjustment (valvas, ignition etc). I noticed before the engine was running way too rich. When I changed sparks, there was oil around the plug on the third cilinder, which isn't ofcourse a good sign. Now these guys adjusted the engine and when I went to pick up the car, I noticed (a lot) of blue smoke upon idling. When the engine is running during a drive, there is no significant smoke, only upon idling... When I brought it, it didn't smoke, but the guy who adjusted it, mentioned the oil consumption and said I should consider an overhaul... Which has been done just before I bought the car (although i don't know if they changed pistons etc)

Any advice of you guys? Could it be that while adjusting, the engine ran hot?

And I'm also looking for a real specialist for overhauling engines in Belgium or in Germany (vincinity of Belgium)... I don't want to have a ready-overhauled engine since my car is matching...

Thanks for some good advice...
 

Markos

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PS: sorry for my not-so-strong english :rolleyes:
Your english is Non-issue, and significantly better the our Dutch!

You mentioned that you noticed this when you picked the car up. I’m guessing you noticed when you first started the car. After driving around for 15 minutes, does it still smoke at idle?

Blue smoke is from oil. Tuning the carbs won’t make the oil go away. If it were the rings then you would get blue smoke while driving. You see it in traffic (in the US - excluding California) on old beaters that leave stoplights.

My guess based on the collective wisdom of others is that the valve guide seals are bad on that cylinder. Oil leaks down when parked. It smokes during idle and you burn off the oil while driving. The the problem is temporarily gone. When you park it, and the problem comes back after sitting for days.

Anyone?
 

teahead

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how many miles on the engine?

If it doesn't blow smoke all the time, just on idle, it may be your valve seals. Or worse, valve guides. The former probably can be changed w/the head on. Not the latter.

If it's the latter and/or bad piston rings, I'd start looking for a low mileage M30B35 motor.
 

dang

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Which has been done just before I bought the car (although i don't know if they changed pistons etc)
Can you get more history from the previous owner? If it had been recently overhauled the shop should be able to notice that. The seller might consider replacing some gaskets as being an overall...
 

Joeneke

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Everyone,

so, I brought it to a specialist in tuning carburators because it wasn't running well on idle and it was quite abrupt going from steady to acceleration. I think it was already burning some oil before, but it didn't show through the exhaust pipe. It was only after they tuned it, that the blue smoke started...

So, it only smokes during idle, not at all while driving... But when it idles, my god, it smokes like an old Lada (no offence).

The engine should have been completely overhauled about 1.500kms ago, i have a photosession of these works (and I contacted the previous owner-restorer).

Yes, there is oil leaking when you let the motor run on idle and it gets hot(ter). It's three cilinders, one, two and three, not the back ones. Plugs did get bit black and greasy...

From what I discover, it could be the valve stems... The exhaust collector also gets wet with oil.

Consumption? Well, since I don't know what oil they have put in, I can only say that it has used about 1L during 1000km approx...

The engine runs fine, no noises, no ticking, acceleration is perfect, ...
I think tomorrow we will do compressiontest and a camera-inspection on the cilinders that leak...
 

Joeneke

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PS:
You see it in traffic (in the US - excluding California) on old beaters that leave stoplights.
Well, Markos, in my case it not only smokes when pulling of, it starts to smoke when I stop, after 10 seconds or so... And it really smokes during the idle, I mean, a lot...
 

dang

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Maybe they fixed a vacuum leak and it's causing more oil to get pulled into the chamber?
 

Stevehose

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Is oil leaking out of the valve cover gasket onto the area of the front 3 plugs? Put a towel up there to check or wipe often to see if it keeps getting oily.
 

Stevehose

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Retorque your valve cover, they warp with age and I have solved this problem by ignoring the tightening sequence in the repair manuals and tighten mine front to back to ensure it spreads out and lays flat.
 

Joeneke

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Retorque your valve cover, they warp with age and I have solved this problem by ignoring the tightening sequence in the repair manuals and tighten mine front to back to ensure it spreads out and lays flat.
I could do that, but I'm afraid that would be a fix from heaven... Because it is specifically only on idling and it starts from about the height of the sparks, not above... It's as if the oil leaks out around the sparks, but I think it comes from where the exhaust is connected on the engine...

Anyway, I'll do the check and get lot's of pictures tomorrow from what i want to say.

But already: a BIG thank you, guys...
 

Stevehose

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One of the front exhaust studs passes through to the inside of the block (I think it is the first stud but not sure paging @sfdon ). It needs to have thread sealant put on it when installed otherwise it can leak as you describe.
 

deQuincey

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i wonder which clear ideas/information you really have about all this

it is difficult to judge what happened to your engine in the past, i have had in my hands freshly renewed carbs from a nut and bolt resto that were terribly wrong (simply a change of gaskets, but nicely rechromed and full of debris and even broken elements inside)

tuning an engine can not make the engine burn oil internally, but maybe if the top cover is misplaced or badly tighten you can have oil burn but outside the engine

you mention a lot of blue smoke when iddling, we assume that smoke came out from the exhaust pipe, is that right ?

have you checked what comes out of your exhaust after a prolongued retention, i.e. you go downhill retaining the car with the engine, then when you first push the accelerator you will have normal smoke or you can get a huge blue cloud, which one do you have ?

on the other hand tuning an engine if done incorrectly can lead to overheating, if you retard ignition too much or if you fix lean combustion

does you mechanic really know what he is doing ? there is probably very little thing worse than a bad/not educated mechanic
 

Honolulu

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Blue smoke on idle... I (used to) resemble that.

Back when I was taking my two kids to school, there would always be a hideous traffic jam on the street in front of the school. I'd sit there in a cloud of blue smoke. No smoke while running (maybe it all dissipated too quickly). I didn't worry about it, just kept the engine oil at the proper level. Yes it used a good deal. Some months later, it stopped smoking.

What happened? Maybe something loose got filled with burnt oil and sealed better. Maybe I had a stuck piston ring and it freed itself. It will be interesting to hear the results of your leak-down test, notice I didn't say compression test... keep us posted.
 
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