Engine Diesels, and Radiator Problem - Third Generation F-Body Message Boards

redtruck18 · 11-06-2009, 12:33 PM

Ok, just got my 1987 RS with a 305, with a brand new eddelbrock carb on it, the first issue is that when the automatic transmission is in park, and the engine is then turned off, the engine will continue to run after shutting it off, its going extremely slow, still runs, i have a hunch that this is caused by carbon buildups, but just want some input on it.

the second issue is that after about a half hour drive at about 60mph, when the car is shut off steam came rushing out from under the hood, upon closer inspection there was antifreeze/water mixture all over the ground under the car, the radiator appears to be solid, and the leak only became evident once the engine reached operating temperature, could this just be faulty hoses?

my current goal for remedy for both of the above problems is A)replace upper and lower radiator hoses, clamps, thermostat, flush the radiator and look for any damage there, im also going to replace the oil with full synthetic in the engine, new oil filter and a new air filter, i also am debating doing a "Power Tune" rinse of the system, this basically involves emptying a can of aresol power tune into the carb until the engine dies or the can is empty, letting it set for a few hours, then cranking it and basically blowing all the carbon out. Does anyone have any other suggestions to solve these problems? Also, does anyone know where i could find replacement shocks for the hatch and hood?

thanks in advance,
joe.

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el_muerte · 11-06-2009, 01:52 PM

For carbon buildups, you can lightly mist water into the carb with the engine running, making sure you give it enough throttle to stay running. For the coolant leak I'd suggest getting under the car with a light and a few rags, try and find where it's coming from before you go replacing parts. Check the hoses and clamps, water pump, water neck, as well as the block heater - I've seen two cars in the past two months leaking antifreeze due to a bad block heater seal. If you can't find anything under the car run it up to operating temperature, then pop the hood and try to pinpoint where the steam is coming from. Just make sure you keep your face away when you open it and don't inhale the fumes.

1A Dan · 11-06-2009, 04:20 PM

I had a dieseling issue when I went to a carbed setup with my holley. First check to make sure you're not idling too high. I knocked my idle down 50-60 rpms and the issue went away

Check your radiator cap for the second issue, spring may be worn out.

lee4354 · 11-06-2009, 04:56 PM

as for the coolant leak, chances are its a split in the radiator that allows it to leak once it gets to operating temperature.

the dieseling is probably due to poor timing. with the car running trying turning the distributer a little each way and shutting of the car and see if that cures the problem

redtruck18 · 11-07-2009, 10:00 PM

Ok, after about 20+ hours of working and cleaning and such after my last post here's the latest. I took it to the car wash to scrub it up and see how it looked once clean (and i must say i was IMPRESSED) the paint which i thought was pretty much done for is in great condition, with only minor imperfections. After a good 3 hours of cleaning etc. i went to start it up... turned over for a second and then just stopped, while making a sorta winding noise, but it wouldnt start up. so after about 3 hours of pulling parts off and running down the road to the local auto parts store to get them tested i decided it had to be the starter... I finally got it to crank and parked it at the auto parts store overnight, this morning I headed back up, and after about 3 hours of pulling the old starter out and putting in the new one (the y-pipe is convienetly placed as to block the starter from removal) it cranked right up. Next: new radiator, upon a nice steamy inspection i decided it had to be leaking from the radiator, and sure enough, new radiator and hoses= no leak. Then it was off to time it... i used the timing light and timed it to one degree advanced, which should be well within normal tolerances(i ran out of daylight and had to say thats good enough for tonight) after a good 15 minute test run to make sure the timing was good (including rapid starts etc.) i decided it was acceptable. Then i turned it off... and it still does this slooooow sputter. It sounds like the engine is still running, but very very very slow, and if i turn the ignition back on, without cranking it, it will run normally. the only way to get it to stop without this sputter is to put the auto tranny in 1st gear, then turn it off. Im lost now, my next idea is to de-carbonize the engine, im thinking this may be causing my problems. But id love advice on what to do. Could it just be timing? Im not sure how timing could affect this if its timed at pretty much 0 degrees ( only advanced SLIGHTLY).

el_muerte · 11-08-2009, 05:17 PM

Probably not timing as the plugs shouldn't be firing at all with the ignition off, regardless of where the timing is set. First I'd try running a cleaner through your engine, Seafoam woks well for this but you could try simply misting some distilled water into the carburetor with the car running. If there's carbon buildup you'll see it on the ground behind the exhaust after cleaning it. If it continues dieseling, make sure your idle mixture is correct and try slowing down the idle a bit. You could also try a cooler thermostat.

redtruck18 · 11-08-2009, 09:23 PM

could it be related to fuel pressure? I noticed today when filling up that there was ALOT of pressure built up when i opened the tank. I replaced the fuel cap and am wondering if replacing the fuel vent canister thingy? or at least pulling it out and having a look? Im starting to notice a pattern, and it only seems to diesel when the engine is warm. ill probably pick up some of this sea foam stuff on my next weekend and give her a go... thanks for the help. if you happen to have more ideas, please let me know.

Joe

el_muerte · 11-09-2009, 02:53 PM

I can't think of a way this would be related to fuel pressure, as excessive pressure would cause a rich idling condition which would likely actually reduce dieseling as the unburned fuel would help cool the combustion chambers. Someone more knowledgeable than me would probably be able to help you with that as I'm not completely sure. In any case, I'd recommend following the steps already suggested before jumping to other conclusions. Also you should get a vented gas cap to prevent the pressure buildup.

redtruck18 · 11-09-2009, 03:05 PM

If i understand the way an HEI distrubitor works, it should fire as long as the engine is rotating? so it makes sense to fire, and im not really jumping to conclusions, im just slowly finding all the quirky things on this car and trying to see if any are connected. I definatly will be doing a carbon cleansing this weekend, i have noticed that if i gas the engine before shutting it off it only diesels 1/3rd of the time... not sure why...

lee4354 · 11-09-2009, 04:23 PM

glad to see you got the coolant leak fixed. i was thinking about your dieseling problem a little more. i think your carb may be the problem. if you timed to straight up or even one degree thats not enough to keep it running, but a faulty carb leaking fuel after the key is off allowing just enough fuel to keep it running will do that too.