Advice on 7.4 Horizon flame arrestor removal/cleaning

[Knot It]

What is the best/easiest process for this? Remove the whole plenum or the riser and exhaust tube? The configuration of the plenum and arrestor are such that there is not room to remove the arrestor because of the exhaust tube and riser are too close as you can see in picture.

I have read many posts on this that dont really give me a clear understanding of which way to go.

It seems that the plenum is the quicker/easier route but I'm not sure what the process for that is. If I do remove the plenum, do I need to replace any gaskets or is it just a few bolts and hoses to remove and replace? Any help would be greatly appreciated as I want to clean the flame arrestors as part of my annual spring maintenance.

Thanks,
Sammy

 

[Skuza]

I too am curious. Never been cleaned in our 12 years of ownership because if this!

 

[Knot It]

WOW. Maybe I'm just a worry wart then. In my reading, I saw several instructions which indicate that this should be done as needed or at least annually. Mine dont look really dirty, but then I dont really have anything to compare it to either. Just want to do the little things I can to keep my boat in good running condition.

 

[acuraguy81]

I would not think the plenum has a gasket. The factory would have in mind that this has to come off for maintenance It looks like you might be able to take the exhaust hose off and wiggle it off. I would clean them with carb cleaner and a air compressor.

 

[Larry]

I have cleaned mine a few times over the last 8 years that I have owned my boat. I have done it both ways, removing the plenum is easy but there are 4 gaskets that it sits on. My gaskets I replaced a few years ago very easily, they didn't seem to "stick" to bad. You don't need to disconnect anything else, there will be enough play with all the other hoses (confirm that the vacuum hoses underneath didn't fall off). I have also removed the risers for periodic replacement, at that time removed and cleaned the flame arrester.

 

[K-DUB]

I ran into this last year on my new boat. It appeared the PO had never cleaned them.
I slid the air cleaner away from the plenum and put a plastic bag between the two to stop anything from getting into the motor.
I put an old towel underneath and saturated the air cleaner with spray carb cleaner. After it soaked for a bit I used an air compressor to blow the debris and dirt through the element onto the towel. Probably not the most thorough method, but avoided any teardown, and seemed to work pretty well.

 

[Knot It]

I have cleaned mine a few times over the last 8 years that I have owned my boat. I have done it both ways, removing the plenum is easy but there are 4 gaskets that it sits on. My gaskets I replaced a few years ago very easily, they didn't seem to "stick" to bad. You don't need to disconnect anything else, there will be enough play with all the other hoses (confirm that the vacuum hoses underneath didn't fall off). I have also removed the risers for periodic replacement, at that time removed and cleaned the flame arrester.

Thanks Larry,
Would it just be as simple as removing the 8 bolts on the top and 2 on each side of the plenum (the ones you can just barely see in the picture above) and then replacing these gaskets...item #17 in this schematic http://www.marinepowerservice.com/B...1999/block_nbr/140/Doc_Part_nbr/809994 96.cfm?

Do I need to use any type of gasket sealer when replacing these?

 

[Larry]

Thanks Larry,
Would it just be as simple as removing the 8 bolts on the top and 2 on each side of the plenum (the ones you can just barely see in the picture above) and then replacing these gaskets...item #17 in this schematic http://www.marinepowerservice.com/B...1999/block_nbr/140/Doc_Part_nbr/809994 96.cfm?

Do I need to use any type of gasket sealer when replacing these?

That's exactly it! Just the Torx head bolts you see and the gaskets do not need any sealant, mine came off very easy... just remember to check the vacum hoses under the plenum (Aft end) are still intact when you reinstall.