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Drastic Solutions

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Rambler Mexicano View Drop Down
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    Posted: Oct/29/2018 at 9:30pm
I have a 1981 VAM Rally GT (Spirit GT) with a 282 inline six since 2005.

Ever since, I've had a problem that just does not allow me to enjoy my car.

There's something that I can only describe as smoke entering the cockpit of my car from the door windows when they're down.

The higher the speed, the worse the smoke gets. It's just a matter of minutes before you start getting irritated eyes coupled with a headache, and imagine the toll on your health in the long run (lung problems).

It was just impossible to drive the car on highways without rolling the windows up. You guys know how the sun and the heat are like here in Mexico. Thus, this means turning the car into a sauna. The car does not have Air Conditioning and even if it did, it would turn the gas mileage into a burden.

At one time, having the car standing still parked outside my house idling, I stepped on the gas standing off the car and I got the smell of the smoke coming towards me and feeling air touching me that was coming from the space between the hood and the fenders.

So I finally connected another dot.

The smoke came from the engine compartment. It got pushed back by the engine cooling system fan itself.

I requested help from friends and mechanics, I got lost of possible causes for this problem, but it just wouldn't go away.

I was told several times my exhausts were leaking. I got them checked out, all possible leaks were fixed, and in the end it would make no diference.

I was told the smoke came from oil dripping from the valve cover gasket and falling on my headers and exhausts. The oil would be burned by the temperature of the exhausts/headers and that would be the smoke I got inside the car. I had the exhausts and headers washed several times and also it wouldn't make any difference.

Others told me some truly ludicrous causes. Such as the exhaust tips, being stock, were too short and the smoke would get into the car through the rear hatch (gasket damaged and not sealing) due to normal smoke/gas dynamics.

More than once I wrote posts on this problem in THIS forum, some of you guys might remember them. The most common diagnosis you guys made based on my descriptions was a possible case of blow-by, engine fumes/gases/smoke going through the piston rings.

After all these years and running in circles in regards to this issue, it's apparaently clear now.

Due to money problems and other priorities, my car sat at a repair shop for two years, out of everything that was repaired at that time were the two rubber caps on top of the valve cover. One cap is used to place the PCV valve and the other is a gas recirculation port that goes to the air cleaner.

The rubber caps my mechanic used were different-looking from the previous ones.

After two years, I picked the car from the shop and took it to a three-hour drive in the highway.

I had the driver's window down and there was no smoke coming inside, in fact I didn't notice it after some after I had arrived to my destination.

It seemed that the problem was finally solved. The rubber caps on top of the valve cover did not seal and smoke was leaking though.

But the happiness didn't last.

The goddamned carburetor starting having trouble after trouble not long after I got the car and it had to be repaired.

That meant having to plug and unplug the hose connecting the air cleaner to the valve cover several times. The rubber cap didn't last any amount of time, it got softened and loose almost immediately.

The smoke returned to the interior of the car.

I was so mad I truly considered SEALING OFF the valve cover hole and removing the hose off the air cleaner.

Buy I am no engineer and I don't want to remove the factory recirculation that goes into in the air cleaner.

While my car is in a very original condition, I soon remembered my valve cover is already modified. Back in 2009 when a mechanic changed the head of my engine in favor a 1984-1986 Jeep unit that originally had the infamous leaky plastic valve cover he CUSTOMIZED the older original metal valve cover so it could be used with the newer head. He had metal inserts welded into the distributor's side of the valve cover to create a flat side coinciding with that of the head.

So now that my valve cover is no longer original, I decided to make a SECOND MODIFICATION to it.

See below.


I kissed the two rubber caps goodbye.

The recirculation hollow at the back of the valve cover got a pipe welded in place to have the hose inserted and fixed with a metal ring with a screw on it to regulate the pressure (what is it called?).

The original PCV valve and the rubber cap were ousted and a NUT was welded on top of the round hollow.

The NUT is used to hold a NISSAN V6 engine PCV valve that is SCREWED in place instead of just being held inside by the rubber cap. Thus, creating a positive seal.

Finally, you just place the hose on the other end of the valve and the PCV system is back online.

Unfortunately I won't be able to test my remodified valve cover in a while.

Right now, I have another engine head in my car with another valve cover (so it can be used).

I won't be able to make the head change to the engine (alongside the cover) until I finally have with me the performance camshaft I am in the process obtaining.

As soon as that is done, I will come back here to report the results.

Hope you found this post interesting.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
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knightflight View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote knightflight Quote  Post ReplyReply Direct Link To This Post Posted: Oct/30/2018 at 11:49pm
First off, I am only giving my 2 cents worth here going by experience to try to help you out, so take it as you will...

Secondly, is the 'ludicrous' example you gave. it is actually not ludicrous at all. That is actually a very common problem. It is a common problem on the early 65-66 Mustangs because the trunk lid hangs over the tail pan about an inch. If you have ever watched wind tunnel tests, there is quite a bit of pressure and turbulence behind the car swirling the air at the tail. The faster you go, the more pressure. If you have your exhaust pipes in the rear, that pressure can send the exhaust fumes into the trunk and through the car. I have lifted many trunk lids with this complaint from customers and rubbed my finger under the trunk lid and showed them the black soot on my finger. I get a shocked look from them every time, so yes the trunk needs to be sealed tightly to prevent the fumes from entering...remember those are EXHAUST fumes though.

Thirdly, regarding oil fumes, or even gas, those can come in though the front. Usually it is from the firewall where holes have been drilled and left unsealed, or factory holes that have been modified, etc. There are many. Also the cowl seal gets overlooked. Most people think that seal is not necessary, but it prevents vapors from entering the cowl screen. Think about that...the air enters the cowl screen and goes directly into the vents in the car, and you end up with the odor. I JUST dealt with this on a customer's '67 Firebird. He couldn't stand the oil smell entering the car. I re-sealed all the areas in the front compartment sections...problem solved. Small ones need to be sealed too.

Fourthly(is that a word?), the window opened or closed affects either of these conditions I mentioned. If the windows are open, the air entering at speeds acts as a venturi and will suck in the air through the trunk in the rear, or the vents in the front. That is why in either of these situations, the closed windows do make the condition seem better.

Lastly.. An engine MUST HAVE the crankcase breathers in place. The crankcase has to breath through those breathers. One is for the inlet, second is for the suction of vapors through the intake. If you plug them off, the engine will build up pressure and blow out oil everywhere. I have see some literally blow the dip stick out of the block, and some will blow gaskets, etc. Do not plug off the engine breathing. You will add more problems to what you already have. The engineers know more than your mechanic, so leave it be.
People always think of a piston moving up and building compression...it does the same going down, along with compression leakage. The crankcase needs to relieve that pressure!

Hope that all helps a bit..
Walt

Edited by knightflight - Oct/31/2018 at 12:00am

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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Oct/31/2018 at 12:40am
Ok. Woah. I think you went way overboard with this.

The two rubber grommets in the valve cover are both for crankcase ventilation. The PCV valve goes in one and the fresh air intake from the air cleaner goes to the other. Proper reproduction rubber grommets are available but sometimes they don't seal perfectly to the valve cover. This never caused smoking problems in my cars, only a minor oil leak. I solved this by installing the rubber grommets with some 'Right Stuff" gasket maker around the outside of the grommet to literally glue/seal them to the valve cover. Absolutely no leaks from them after doing that. I also cut a new cork gasket for the oil filler cap and there are absolutely no leaks from it after that. It's also possible that valve cover is not properly sealing to the cylinder head, especially after your mechanic welded on modifications to that valve cover. The heat from welding likely warped the heck out of it and it doesn't seal right any more. 

Even if none of this sealed and the engine vented all it's crankcase vapors and smoke to the atmosphere, it should not be severe enough to cause driver and passenger discomfort unless the passenger compartment of the car is poorly sealed from the engine compartment (holes in the firewall) or if the engine is creating far more crankcase vapors and smoke than it should due to poor piston ring sealing. Engines used to vent their crankcase down through a pipe under the car in the days before PCV. They didn't create enough smoke or vapors to disturb people inside the car so long as the car was sealed well and the engine in good condition. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pacerman Quote  Post ReplyReply Direct Link To This Post Posted: Oct/31/2018 at 11:58am
There is a reason that AMC routed the exhaust behind the rear wheel on convertibles and station wagons instead of under the rear bumper.  Joe
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Oct/31/2018 at 1:38pm
Thanks guys for your responses.

Originally posted by knightflight knightflight wrote:

First off, I am only giving my 2 cents worth here going by experience to try to help you out, so take it as you will...
Secondly, is the 'ludicrous' example you gave. it is actually not ludicrous at all. That is actually a very common problem. It is a common problem on the early 65-66 Mustangs because the trunk lid hangs over the tail pan about an inch. If you have ever watched wind tunnel tests, there is quite a bit of pressure and turbulence behind the car swirling the air at the tail. The faster you go, the more pressure. If you have your exhaust pipes in the rear, that pressure can send the exhaust fumes into the trunk and through the car. I have lifted many trunk lids with this complaint from customers and rubbed my finger under the trunk lid and showed them the black soot on my finger. I get a shocked look from them every time, so yes the trunk needs to be sealed tightly to prevent the fumes from entering...remember those are EXHAUST fumes though.

Thirdly, regarding oil fumes, or even gas, those can come in though the front. Usually it is from the firewall where holes have been drilled and left unsealed, or factory holes that have been modified, etc. There are many. Also the cowl seal gets overlooked. Most people think that seal is not necessary, but it prevents vapors from entering the cowl screen. Think about that...the air enters the cowl screen and goes directly into the vents in the car, and you end up with the odor. I JUST dealt with this on a customer's '67 Firebird. He couldn't stand the oil smell entering the car. I re-sealed all the areas in the front compartment sections...problem solved. Small ones need to be sealed too.

Fourthly(is that a word?), the window opened or closed affects either of these conditions I mentioned. If the windows are open, the air entering at speeds acts as a venturi and will suck in the air through the trunk in the rear, or the vents in the front. That is why in either of these situations, the closed windows do make the condition seem better.

Lastly.. An engine MUST HAVE the crankcase breathers in place. The crankcase has to breath through those breathers. One is for the inlet, second is for the suction of vapors through the intake. If you plug them off, the engine will build up pressure and blow out oil everywhere. I have see some literally blow the dip stick out of the block, and some will blow gaskets, etc. Do not plug off the engine breathing. You will add more problems to what you already have. The engineers know more than your mechanic, so leave it be.
People always think of a piston moving up and building compression...it does the same going down, along with compression leakage. The crankcase needs to relieve that pressure!

Hope that all helps a bit..
Walt


Thank you very much Walt,

I thought the gas dynamics issue was ludicrous because of all of the negative experiences I've had from unreliable mechanics in regards to my car. You explained it all pretty well.

I need to repaint and work on the body of my car, when that happens I'll fully take care of that possibility (smoke/fumes entering through the hatch).

I've had my firewall chcked several times. The smoke/fumes odor does away everytime I roll up my windows, if my built-in ventilation vents are open or closed it makes no difference. I've turned on the heater at ambient temperature with the windows closed and fortunately, no smoke odor appears. You said the windows affect the entering of gas, so I have to check further to know the truth.

I just can't understand how there was no smoke coming inside the car in that three-hour highway drive I took.

Originally posted by FSJunkie FSJunkie wrote:

Ok. Woah. I think you went way overboard with this.

The two rubber grommets in the valve cover are both for crankcase ventilation. The PCV valve goes in one and the fresh air intake from the air cleaner goes to the other. Proper reproduction rubber grommets are available but sometimes they don't seal perfectly to the valve cover. This never caused smoking problems in my cars, only a minor oil leak. I solved this by installing the rubber grommets with some 'Right Stuff" gasket maker around the outside of the grommet to literally glue/seal them to the valve cover. Absolutely no leaks from them after doing that. I also cut a new cork gasket for the oil filler cap and there are absolutely no leaks from it after that. It's also possible that valve cover is not properly sealing to the cylinder head, especially after your mechanic welded on modifications to that valve cover. The heat from welding likely warped the heck out of it and it doesn't seal right any more. 

Even if none of this sealed and the engine vented all it's crankcase vapors and smoke to the atmosphere, it should not be severe enough to cause driver and passenger discomfort unless the passenger compartment of the car is poorly sealed from the engine compartment (holes in the firewall) or if the engine is creating far more crankcase vapors and smoke than it should due to poor piston ring sealing. Engines used to vent their crankcase down through a pipe under the car in the days before PCV. They didn't create enough smoke or vapors to disturb people inside the car so long as the car was sealed well and the engine in good condition. 

Thanks, as far as I've checked, my then mechanic did a pretty good job in the customization of the valve cover, since I've never had any oil leaks since.

I grabbed a hose and passed one end of it around the valve cover gasket with the engine idling and put the other end in my ear. I could not hear any sound of gases sipping through.

I did not cancel out the PCV system and the recirculation of the crankcase, I simply modified it not to require the rubber grommets and thus be able to discard a possibility of smoke/fume leaking through them.

Originally posted by pacerman pacerman wrote:

There is a reason that AMC routed the exhaust behind the rear wheel on convertibles and station wagons instead of under the rear bumper.  Joe


I didn't know that. With all the information you guys are sharing, now I see why that happened.


Edited by Rambler Mexicano - Oct/31/2018 at 1:41pm
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Nov/15/2018 at 3:15pm
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Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
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