HELP! Smoke from my 208GT4

CLAES:

White/gray smoke could be oil ... check you oil level. Check your oil pressure to ensure that it remains within specifications at idle and at speed. You would not want the pressure to be higher than normal. Have you changed brand or viscosity of oil prior to noticing the smoke?

Does the vehicle smoke when you first start it? If so, and it has been doing so for some time, you might check for worn valve guides and seals ... The car may also smoke if you were driving the car hard then allow it to slow down for a corner while still in gear and then get back on the gas due to worn guides and seals.

Has the car been smoking a bit and is now getting worse or did the smoking just suddenly begin? If there was no smoke recently and you have not changed oil brand or viscosity and the oil pressure is within normal limits, you may have a damaged ring, however, I would suspect that one would normally notice some smoking at all engine speeds with a damaged or broken ring.

You may need to have a leakdown test done to determine what might be causing the smoke.

Best wishes

 

Claes:

Sorry about sending my first message without a message ... the Shift Key stuck while I was typing and when I was trying to fiqure that out I hit a key that sent nothing but your name. While I was trying to edit the first message, you must have clicked on the site ... sorry about that!

I have edited the first message and hope that it helps.

Some additional information may help diagnose the smoke from your GT4 ... I clicked on your profile and saw your car: a real beauty! If you have the mileage it may help ... the year model may help and any recent service that the vehicle may have had may help.

Best wishes

 

White / gray smoke means coolant to me. You may have a blown head gasket. That's the only way you'd get coolant in the exhaust. If it is as I suspect, check the pressure at the radiator cap. Since a coolant passage is now connected to a cylinder, you should notice higher than normal pressure. I hope i'm wrong. Good luck.

 

Claes,

without any more information, I would agree with Tom that it is coolant?

If only a small amount of water is getting in, it won't be so noticable at High rpms as it will be diluted by the higher exhaust flow. But if rpms are low, coolant may collect in the exhaust, so that when you accelerate you get lots of smoke.

The smoke has to be coming from somewhere, so your coolant level or your oil level should be dropping.

Dan

 

Claes:

As you mention that you are going to check the carbs ...

You might check the carb jetting if you have changed elevation by a considerable amount from where the car was normally driven. You would usually experience a dark smoke from the exhaust if the jetting is allowing too much fuel into the mixture (rich mixture) and a puff of white smoke if the air jetting is too great for the altitude (lean mixture) ... You may also check the plugs in an effort to diagnose carb problems.

Some of the older model cars, pre-308, that have been imported from markets like Switzerland and other alpine markets to the US have had strange problems due to the carb jetting difference ... usually, however, there is a noticable loss of power from high altitude jetting used at at sea level.

The more pictures of your car, the better it looks! It really is a beautiful vehicle.

Keep us posted

Best wishes

 

Claes,

As a GENERAL rule, white smoke is oil. This is regardless of whether it is synthetic or mineral.

If the white smoke is on acceleration, then it is most likely rings. If it is on backing off, or idle, or light throttle application, then it is inlet valve guides.

If it is all the time, then it is most likely a head gasket (or cracked head)

Coolant generally does not "smoke" although major leaks will appear as steam.

The way to approach any problem like this is to simply consider the various pressures experienced by different cavities in the engine under different conditions.

The oil galleries have oil pressurised at between 10 and 80 psi depending on temp and rpm. These sorts of pressures will always be higher than cylinder pressure at some stage in the 4 cycles, regardless of throttle opening. Therefore, a busted head gasket COULD allow oil to enter the combustion chamber at all times. The way to test for this is, I guess, to have a static cylinder pressure test performed. Often also, a dead head gasket will also mean that coolant chambers are compromised, so one might find oil in the coolant, or combustion gasses in the coolant, or simply be loosing coolant

In low throttle opening situations, the pressure in the inlet manifold is very low - ie a partial vacuum. In these situations, a leaky inlet valve guide will allow oil to be sucked through, and then be burned. In WOT situations, the inlet manifold pressure rises to almost atmospheric pressure, so there is no "sucking through" of oil via the inlet valve guides.

When the rings are the cause of the problem, the source of the oil is from the oil rings which are designed to leave a thin layer of oil on the cylinder wall for lubrication. Generally the compression rings will wipe this off on their way down. If they are "gone" then they do not wipe as they should, so oil gets into the combustion chamber. This is worst under WOT situations as the crankcase pressure from blow by gasses of the other cylinders will be higher, thus increasing the effect.

The final possibility is, obviously, that I am completely off track. The above is simply what I understand to be the case, and is quite possibly wrong. I would be delighted if those more knowledgeable than I were to correct me. At the very least I will learn something. Regardless of this, I have always believed that the way to approach problems like this is logically.

Hope this helps a little, Dave.