Dieseling

[Bragor188]

My 1967 BJ8 with 75,000 miles has been dieseling when I turn off the ignition. I have tried turning off the ignition with the car in first, but that has only reduced but not eliminated the dieseling. I have been using Premium Unleaded gasoline. Any suggestions as to what I should do before it does any real damage?

 

[bighly]

Check your timing

 

[Basil]

Hi Stuart,
First, welcome to the forum! As bighly said, check your timing first. If that's off, that's an easy fix. I'm sure you will get others to chime in with possibilities, and in the interest of full disclosure, I'm not a Healey guy. However, one other thing that I have had trouble with in the past that caused dieseling is excessive carbon build up on the tops of the pistons and in the tops of the combustion chambers. I had this problem with a 96 Saturn and the dealership told me to get some "top end" cleaner. You might want to pull a spark plug and see if you can see the tops of the pistons for excess carbon.

What happenes is (as I understand it), some of the excess carbon continues to glow like camp fire embers after you shut to engine off. The glowing embers act to continue to ignite the fuel mixture for a period of time; thus, the engine continues to run for a while after.

In one case, on my 67 EType, I had this problem once many years ago and ended up pulling the head and just cleaning up the piston tops and chambers. (I went ahead and had a valve job as long as I had the head off).

Good luck and do keep us posted as you solve th eproblem so that others (even us non-Healey vermin) can learn from your experience.

Cheers,
Basil

[ 04-25-2003: Message edited by: Basil ]

[ 04-25-2003: Message edited by: Basil ]</p>

 

[aeronca65t]

...also make sure idle speed is not too high. (should be around 650 or so).

and....Welcome! You are about 90 minutes drive from the Moss Britfest in Succasunna, NJ next weekend (on May 3)...lots of big Healeys...if you are free, you would probably enjoy it.

 

[Basil]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by aeronca65t:
...also make sure idle speed is not too high. (should be around 650 or so).

and....Welcome! You are about 90 minutes drive from the Moss Britfest in Succasunna, NJ next weekend (on May 3)...lots of big Healeys...if you are free, you would probably enjoy it.<hr></blockquote>

If I can get you some BCF cards, could you hend some out if you go to that event? Also, be sure to take some pictures!

Basil

 

[Dave Russell]

Hi Stuart,

Welcome to a great forum. For your run-on problem, even small changes in fuel mixture, fuel octane, timing, can affect this problem.
see this link;

https://www.faqs.org/faqs/autos/gasoline-faq/part3/preamble.html

Go to the bottom of part 3 & click on 8, "How can I identify & cure other fuel-related problems." Section 8.2, paragraph 5. Probably more than you ever wanted to know about motor fuels.
D

 

[jjbank]

Stuart,
I am presently having the same problem with my Healey(64BJ8). What I have been doing the last 3 years to prevent diesling(run-on) is this. Every three fill-ups I add about 1/2 a bottle (4 OZ. I believe) of Bardahl's Octane Boost. This is actually 1/2 the recommended amount. This works fine for me. I have not had knocking in 3 years. I just forgot to bring the Bardahl's with me the last fillup. I do not know if there are any repercussions from doing this?

 

[Bragor188]

Thank you all. I added half a can of Octane Boost and, although I expected it to take a while to work, it work the first time I turned the car off