Author Topic: Exhaust joints  (Read 1596 times)


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Re: Exhaust joints
« Reply #15 on: March 01, 2019, 03:11:04 PM »

......That joint reaches 500f under heavy load and it cooks the silicone.....

Wow, I barely see 320F with my IR thermometer.  That's a 6/1 loaded to about 2,800watts and a 195F coolant thermostat

There is high temp masonry silicone for fireplaces, good to 900F, glop that onto some fiberglass fender repair tape, and you could have success.  I had a muffler shop make some flex couplings that clamp on and they are fine.

John (Boston)

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Re: Exhaust joints
« Reply #16 on: March 05, 2019, 10:52:39 PM »
I used stainless band clamps (got them at a truck and bus supply house) and high temp pellet stove silicone.  I put the silicone around the pipe joints and at the splits in the band clamps (which you shouldn't need to do - those clamps seal pretty well on their own).  I still had mysterious exhaust smells from somewhere.

I took apart and remade the exhaust joints.  They all looked good - you could see where the silicone had sealed nicely.  They were a bugger to get apart.  I had already screwed sheet metal screws (with silicone) into the muffler weep holes.  Still had smells.

I thought it might be blowby so I connected the crank case vent to the intake - nope, not that.  Then I thought it might be valve overlap so I extended the intake by four feet or so - nope, not that either...  I gave up and moved the beast out of the house.

Now I wonder if the exhaust was permeating its way through the walls of the house and getting back in from outside.  Because, with the engine outside, if the wind blows the right way I swear I can smell exhaust in the house - and the engine is 50 feet away.  My exhaust pipe only went about 10 feet away from the house (when the engine was inside) so maybe that was it.

The odd thing is that I can run my little Cummins 4BT (in a Step Van) right outside (about 10 feet away) and I get no smell.

-John (Boston)
Metro 6/1 (genset)
Cummins 6BT (89 Dodge truck, bought it new)
Cummins 4BT (91 Oshkosh bread truck)
Kubota D1005 (B2320 tractor)