M38 trouble on hot days

JIML · Post by **JIML** » Sat Jul 28, 2012 3:12 pm

I'm having difficulty with my 52 M38 at higher ambient air temperature; >90. She initially starts fine, runs great until slowing down from highway speeds to an idle; then doesn't want to idle, sometimes quits. Also, it is then more difficult to start, but once it gets going does fine again at highway speeds.

On cooler days, runs perfect.

I'm kind of scratching my head on this one. I've considered fuel tank/cap venting, re-adjusted the idle; tried leaner and richer, and considered float level. Engine temp runs a solid 180. Any thoughts would be appreciated.

Jim

Post by **wesk** » Sat Jul 28, 2012 10:24 pm

Check the heat riser under the intake. May be stuck in open (heat on) position.

The little gray arm with the round end on it.

JIML · Post by **JIML** » Sun Jul 29, 2012 5:54 pm

Thank you very much Wes, I'll take a look.

Jim

jeeptj1 · Post by **jeeptj1** » Sun Jul 29, 2012 6:08 pm

Wes, my heat riser is toward the valve cover and all the way in the up position and I haven't drove it in acouple of days . Would that be correct position or incorrect. Thanks John jr

Post by **wesk** » Sun Jul 29, 2012 8:43 pm

Should be towards the fender. Is it frozen or free?

jeeptj1 · Post by **jeeptj1** » Mon Jul 30, 2012 8:20 am

Wes, it's free but definitely towards the valve cover. Can this be put on backwards. Drove it alittle today and it seems like it was starting to sag down . Will try to get a good picture of it. It also looks like it has a small piece of asbestos tied onto it for some reason. Thanks John jr

Post by **wesk** » Mon Jul 30, 2012 11:10 pm

The mechanism can be assembled incorrectly and the only way to be sure is to split the intake/exhaust and look at the valve. To troubleshoot try tying it first full travel one way then the other and test drive it.

jeeptj1 · Post by **jeeptj1** » Tue Jul 31, 2012 2:45 am

Wes, thanks I will try it. John jr