Anyone had this 454 problem?

[Pete Peterson]

We have owned a 1985 Midas with a 454 motor for several years.  The previous owner told us that there was a small problem, it would "pop back through the carb" under load.  I tried lots of things and finally found the culprit.  Manifold heat was so hot it would cause failure of the number 7 spark plug boot.  The splash shields on the right side of the motor have been removed I assume in an effort to let some of the engine heat escape.   I have finally found a way to keep the heat from attacking the boot.  I use the heavy duty boot, place it inside of the heat sock (used on race cars and such), and fill the heat sock with silicone designed for wood stoves.  It is a little unusual I guess, but it does work and has for a couple of years. I have asked a number of people and have been told that it is a motor home issue caused by the dog house engine cover and that the 454 was redesigned around that time to increase engine heat to increase millage.  My question remains, is it just my 454 or have other people had the same problem?  Any other thoughts?   As I say, I have been able to get past the problem just curious.  Thanks, Pete  (The Drive-by Tourists)

[William Briggs]

Pat, thanks for your excellent comments. My 454 has the "almost-vapor lock" problem (stop a few minutes at a stop light, then accelerate, but the engine cuts out), and the "hot-starter" problem (turn off the engine to fuel, then try to restart it while the engine is hot), and the dieseling problem. The previous owner has done a lot of work on the passenger side of the engine to get more airflow to that area. Maybe that's why I don't have as severe problems as others do.

 

You mentioned running a higher-octane gasoline, Pat. I was curious if anyone has any advice. I'm currently running 85, but could be talked into 87 octane if needed. Do you think the 85-octane is contributing to the dieseling problems?

[William Briggs]

Pat, I'm at a half-tank of 85 octane. So I will fill with the highest octane available when I move the motorhome, then let you know if it solves the dieseling problem.

 

Pete and others >> I appreciate this thread. It's amazing how we all share the exact same issues with the 454 engine.

[Michael K.]

THANK YOU FOR THIS! My 1989 P-30 Chevy has this exact problem. I assumed it was a clogged fuel filter, but now that I see this thread it makes sense. Of course the motor would cool down while I changed the filter, so it would run fine for awhile after. Thanks again!

[Pete Peterson]

I am glad I could help a little, here are some other things I found in the past few years that are also heat related.  The starters (actually the solenoid) are heat sensitive.  This summer we took a short trip (just under 100 miles) and the ambient temperature was in the low 90 degree range.  On the interstate and towing our old pontoon boat, with that temperature things got a little heated.  I was taking it easy but still the temperature was building on hills and cooling on the down side...never in the red, but getting there.  OK, we stopped to top off the fuel and when we got ready to leave there was no response from the starter....the new starter I had installed last fall by the way because it had failed last fall.  I was ready to pull the starter at the pump and head to the parts store and a nice fellow at the counter told me of the "hammer trick".  You need two people, one to work the ignition key the other to whack the starter to break the solenoid loose...in our case, the starter had cooled enough by this time it started on it's own.  I installed a heat shield blanker when I again changed the starter and following the trip we had the same problem with the new starter...we were ready with the hammer and it started right up.  After we got home I switched to the Ford style solenoid, it is now mounted in a cooler spot and so far so good.  I also was given another starter and I have it stored in the M.H. just in case.  I had some difficulties with the exhaust seal at the head pipe in the past and attribute some of those heat issues back to the seals.  That being said, I am still glad that I found out about the remote solenoid ( diagrams available on the internet ).  I left the heat blanket in place, still glad that I installed the heat shielding on the plug wire.  By the way, the "hammer trick" also works TEMPORARILY SOME TIMES on in tank fuel pumps.  Keep in mind it only works some times and only for a limited time.  If it is the fuel tank, it is usually in the center of the bottom of the tank.  I hope you never need this information again but maybe someone else can also benefit.  Enjoy your travels....Pete and Gigi, your Drive-By Tourists