1970 Buick Skylark Dieseling

[Guest]

I have a 1970 buick skylark which diesels a lot.<P>I just changed the plugs which were completely filled with deposit .<P>But it still diesels <BR>the timing was redone on it but it still diesels , However the enging doesn't keep it's timing all that great , any suggestions ???????

[fordee9r (Ron Springstead)]

Hey Phil,<P>If your plugs were loaded with deposits, chances are there are also similar deposits in the combustion chamber. The first remedy that comes to mind is the old Coke bottle of water trick. If you're not familiar with it, find someone who is before trying it on your own.<P>Another trick I've used on "Old Lady" cars is to find a stretch of road where there isn't a lot of traffic. While cruising at about 40 MPH, I mash the gas pedal and go into passing gear. I hold it down untill it finally shifts into high gear. You'd be amazed at the cloud of crap that comes out behind! I repeat this several times untill the air is clear behind.<P>Some cars of your era came with an anti-dieseling solenoid. If yours has one, make sure it is working!<P>Hope this helps...

[Guest]

indeed this coke bottle trick sounds intriguing , what is it ???<BR>

[novaman]

It is dumping water down the carb with the engine running. The reason fordee9r said "If you're not familiar with it, find someone who is before trying it on your own" is you can <B>damage</B> the engine if not careful. If you get too much water you can hydraulically lock the engine, possibly damage rings, valves, pushrods. <P>The idea is the water since it don't burn will knock the junk out of the cylinders. That's the short version.

[novaman]

Just thought of something. With your problem is it dieseling (continues to run after shutting of the car) or is it pinging or spark knocking (sounds like guy under your hood with a hammer usally under acceleration)? The reason I'm asking is you said about the deposits on the plug and you also said it doesn't keep time good. The timing could be worn timing chain and/or gear. I think it about that time they started using plastic teeth. (don't buy a replacement of this type. it don't cost much more for real teeth.) two other places can be the distributor itself or the gears on the camshaft and distributor.

[Guest]

it keep running after the ignition is off , but the engine runs in reverse ...<P>plastic teeth on a timing chain , ??? <P>i also suspected the timing chain but i had it verified and the mech said it was fine<P>I was thinking about changing the Cap and rotor , anything i should change in the distributor , like the tree maybe ???

[novaman]

(for your infromation)You don't need to start a new post when you have another question regaurding the same topic. You'll get the hang of things here. Glad you registered.<BR>To check your intake and gaskets for a vacuum leak you can use a squirt bottle and spray along the edges. if the engine speed changes when you hit a certain place there is a leak there. I relly don't think it is your problem. Unfortunely I don't have a service manual here at home. they are in my (and my Dad's) shop. <BR>If you will let me know what size engine you have I'll try to post an answer late tomorrow evening. <BR>I have my first night class at the local college so it will be late.

[novaman]

I didn't forget you. I didn't get the book due to time and I had my Dodge truck with the Cummins diesel. I didn't want to distrub the nieghbor's kids.(yesterday was the first day back in school) The driveway is about 15 feet outside thier windows. I'll get it tomorrow.

[Guest]

it's a 350 <P>and well , we tried shooting brake cleaner once on the intake and it did increase the speed , but then we did it again 2 months later and nothing like if it was a sealed intake<P><BR>

[novaman]

Sorry it took me so long. I finally got to the shop and got the manual. Not helpful . I've got A friend that might have some ideas but unfortunely he is hard to get a hold of. I'm hopeful that we will be on the tour our club is having on Sunday. If so I'll ask him.

[Guest]

Being a member of the "older" generation who was buying that era's cars new, I thought dieseling was SOP. It was a problem then and I guess it still is.<P>Funny that doesn't happen with my '14. ~ hvs

[Guest]

You've gotten some pretty good pointers here, so I'll stay out of this for now.<P>What the water does is turn to steam and basically steam clean your cylinders, valves and passage ways. Engine should be at wide open throttle or thereabouts.

[Guest Hal Davis (MODEL A HAL)]

Try a tank of 93 octane and see if that helps.

[Guest]

When working on cars of this era the most common cause of dieseling that I found was that the idle was too fast. Dieseling can be very damaging to an engine. Until you get it cleared up shut the engine off with it still in gear this will usually stall it (automatic trans). Al

[Guest]

Al has it right---idling too fast

[Guest]

The common causes of dieseling are: incorrect timing, idle speed too fast, high compression. You said the timing seems to vary-if it is indeed not stable then something is wrong.Idle speed is very easy to check and decrease. Your car was built at a time when engines had high compression. If the engine has never been apart and has frequently been driven around town then it is possible thatcarbon buildup in the combustion chambers has actually increased the compression level above what it was in 1970. Suggestions: get a second opinion on the timing something appears to be wrong here, try a higher octane gas, fill the tank with Chevron gas and drive at 70 mph for at least 2 hours. The latter will clean your engine without the abuse of high revs from downshifting.

[The Old Guy]

I used to have fun with cars like yours ,as the easiest way to make them run well was to run the wheels off them. I would fill the tank with premium and if I couldn't find a road to run REALLY fast, I would leave it in L2and wind it up to a decent RPM and let it run. That is the simplest way ,and it's FUN

[Guest Albert]

Yes the water & coke bottle does do a nice job at cleaning the upper cylinder's/valves(just look at the top(s) of the piston after you blow a head gasket). As far as the timing gear watch you oil drain pan for white chunks of plastic when you do your oil change. Remember when you do the timing to plugg the vacuum hose to the distributer and keep the rpms below the point when the mechanial advance kicks in.

[Guest]

Baack in the 70s this was a very common problem. The manufacturers found that if the butterfly closed completely - no air entering - when you shut down motor it would be ok. So they added an idle solenoid to the idle stop that held the butterfly open to where it was adjusted for good idle. When ignition was shut off it would retract - the power being shut off - and the butterfly would be completely closed. The solenoid was always energized when the ignition was on. My 75 Buick 350 2bbl did not come with one but as the engine aged I had to put one on. The tip about leaving it in drive before shutting off works because the engine idle is reduced.<BR>My 85 Dodge Ramcharger came with one from the factory.