Completely Stumped....

[Don Moyer]

Good for you, Kurt! I hope our Webmaster can give this posting his 5 star rating. At risk of repeating myself, I'm really quite sure that 75% of the Atomic 4 fleet is suffering some level of performance reduction due to various degrees of elevated exhaust back pressure. Symptoms range from sooty plugs, caramelized goo forming on intake valve stems, and eventually loss of power as in your case.

Don

[High Hopes]

I have my A4 back onboard my boat, but not yet connected. I think I will suck/blow out my exhaust system with the shop vac and make sure everything is clear.

Congrats on your find, Kurt.

[Kurt]

Just follow up on this issue as promised for the archives. Hot exhaust has been replaced and engine runs great - lots of power now. We dropped the old hot exhaust section on the ground and a bunch of crud came out of it. Just replaced the whole section with new pipe. So, don't rule out exhaust restrictions as causes for power loss issues, particularly when you have power loss both in neutral and under load. Very easy to diagnose - just remove the exhaust flange, turn off the water intake and fire the engine up for a few seconds. If your problems disappear, you have an exhaust restriction. So strange as my engine ran fine a year and a half ago and just recently started having intermittent power loss issues and then quickly progressed to constant power loss issues. I would have guessed that this type of restriction would build up gradually over time - guess that probably happens, but doesn't necessarily manifest as performance issues until serious restriction has accumulated. Hope this post helps others out facing similar issues!

[Administrator]

Hi, Kurt:

Way to go!

Did you replace the exhaust hose as well as the hot section?

Bill

[Kurt]

Bill -- yes, I actually replaced all of the exhaust hose prior to replacing the hot section as it had the date 1976 stamped on it, looked original and the metal liner was rusting and popping out of the rubber hose. That obviously didn't solve my problem, but it was the first thing I did cause it was less challenging and needed to be done anyway. So, yep, entire exhaust is new with the exception of the good 'ol water lift muffler.