Engine Exhaust Heat

[Keystone]

I've got a Kohler Agies model LH775S(31 horse, EFI, liquid cooled) that runs a carpet cleaning unit. The system was manufactured in 2006 and has approx 2600 hours on it. I have had to replace the exhaust manifold numerous times. The pipes are cherry red under normal operating conditions and eventually they become brittle and crack. This system does not have the OEM exhaust, rather a custom stainless steel manifold. My local certified and premier Kolher mechanic says the engine and EFI are operating according to specs. I am wonder if it is allowing to much fuel to get into the manifold where it is then burned causing the excess heat. Can the EFI be re-programmed to reduce the fuel and still have the engine run properly? Any thoughts or ideas is appreciated. By the way it has the Bosch EFI.

Model LH775S
Spec #LH775-0001
Serial #3610009571
manuf 04/10/2006

[wristpin]

Had a similar issue with a BS Vanguard twin on a carpet washer a few years back.
The bottom line was that the installation had not been submitted to or approved by Briggs either in the US of here in the UK and was "swallowing " its own hot air and exhaust gases.
It looked to be on a skid unit and I told the guy that if it would slide out (with our lift truck) I would see what we could do but he wanted it fixed there and then in his van - end of!!!!!!!!.

[Keystone]

To my knowlegde this application has been approved by Kohler. I had some warranty work done some years ago and Kohler cover the work.

[bgsengine]

Depends on what the warranty work involved, and of course the dealer could simply neglect to mention to Kohler that it did not have a factory approved exhaust design installed.

Stainless Steel is a really bad choice for exhaust on these machines. even OEM built exhaust had problems (Some "Collector Edition" tractors I used to service all ended up needing non-stainless exhaust installed, tractor manufacturer put out a service bulletin on the issue - they originally installed stainless steel exhaust pipes with a chromed muffler to make things "pretty") - your average Stainless Steel just does not hold up well to heating/cooling cycles inherent to such machines -there are cars and aircraft with stainless exhaust, but they use a different metallurgy or type of steel designed for the purpose, and the pipes have liners - multiple layered pipe. If you HAVE to have stainless steel pipes, I would suggest finding inner liners or mild steel stubs to clamp the pipes to.

Better to get yourself an OEM exhaust manifold. Forget "pretty" and go for "Functional"

[Keystone]

Unfortunately there is no room for OEM exhaust in this application.

[gatcoequip]

A glowing red hot exhaust manifold is due to NOT Enough fuel , rather than to much. Believe it or not extra fuel is used to cool the exhaust system. In the modern day EPA engine there is very little extra fuel for that purpose. Prehaps you could install a cooling fan light what is used in modern car raditors.

[Keystone]

As an old timer and going back to my early days as an auto mechanic we typically felt that over hot exhaust gases were caused by a lean fuel mixture. I thought it odd that a number of local mechanics are now saying it is excess fuel. I have also had a number say that it is very common to have the exhaust glow red on many of these small engines.

[smallen]

we have worked on quite a few of these truck mounted carpet cleaners, the exhaust manifolds are a week leak, some have too high back pressure from design,
some have no way to absorb engine,vacuum pump vibrations causing cracking at the heat exchangers and silencers, we had a 2012 truck that had exh problem when it was new, manufacture said they build them to kohler specs, we contacted kohler application engineers and they never heard of this company, they did contact them and then manufacturer agreed to change the exhaust manifold

[stienut13]

Hi all,

Are these exhaust diameters larger than stock? I'm thinking back pressure problem, or lack there-of. Obviously wrong metal type, configuration, lack of ventilation , too. Just another thought for the pile.

Jim

[Keystone]

Pressure was checked at the O2 sensor and their was no back pressure to speak of. I believe OEM exhaust has two seperate tubes off the heads to a muffler. This manifold has the two come together into a collector and then down stream in an 1.5" pipe. Them failure comes after the collector.