682 CH18 repower heat issue

sorner · #1 08-13-2017, 07:09 PM

My 682 frankentractor has encountered a problem. Today I mowed extensively with it for the first time and when I stopped after about 45 minutes I smelled plastic burning and saw some smoke. I opened the hood to look and I found my air filter cover melted on the front and it looks like the valve covers started to melt. Is there an issue with running these engines with the side covers on? It's not an airflow issue because I cleaned under the tins when I built the tractor. I feel like when the sides are on too much heat is getting trapped under the hood. I left it cool and ran it with the sides off and it seem to melt anything worse. I don't want to run it with the side covers off unless that's my only choice. That's not really a solution in my mind.

R Bedell · #2 08-13-2017, 07:30 PM

How about some pictures...??

cubs-n-bxrs · #3 08-13-2017, 08:06 PM

Did you use a foam heat shield in between the flywheel shroud and the firewall? Otherwise it will just suck hot air from the front of the engine into the flywheel. BTDT

darkminion_17 · #4 08-13-2017, 08:12 PM

I think Frankenstein smelled a little when he burned, there must be an issue with the cowling for the muffler it's not venting out the front of the tractor correctly

Sam Mac · #5 08-13-2017, 09:03 PM

Ducting is important, both inlet and exhaust. Lets see some pics of what you did.

sorner · #6 08-13-2017, 10:06 PM

Well it's dark now so no pictures. But there is no foam between the firewall and engine. what is recommended there as a replacement? I have a good 2"-3" between it and the engine. The heat though is coming up behind the heat shield for the muffler. I hold my hand there above the governor linkage after running it and it burns my hand. My 1864 isn't quite that hot.

sorner · #7 08-13-2017, 10:41 PM

It just occurred to me, and I did some searching on the forum and found suggestions for what to use for the foam.

I realized the 682 has solid side covers and the frame had a mesh on the bottom to allow air in. I used a 1641 frame which has solid steel sheet metal under there. So I'm probably not letting any air in to get taken up into the engine cooling fins and with the side covers off there is enough air flow to keep the engine cooler.

farmall fred · #8 08-13-2017, 10:53 PM

You will need to add the foam between the firewall and engine tins. Also make sure that the seal or weather strip between the firewall and side covers is in place. For the foam strip I used some 1 1/2 thick dense foam I bought for padding seats to make seal for the firewall to engine. I glued it to the firewall with weather strip cement. Are you using the firewall from the 682? I have done three command conversions and they do run warm but they are no worse than the KT or Mag engines. Good luck
Tom

cubby102 · #9 08-14-2017, 01:15 AM

my 782 that i swapped a ch18 in got real hot without the heat sheild on it once i installed the heat shield for the muffler i noticed no difference from a kt
for the record i did not have any foam between the firewall and tins..

sorner · #10 08-14-2017, 06:47 AM

Quote:

Originally Posted by cubby102

my 782 that i swapped a ch18 in got real hot without the heat sheild on it once i installed the heat shield for the muffler i noticed no difference from a kt
for the record i did not have any foam between the firewall and tins..

Is that with or without the side covers? I ran mine without the muffler heat shield for a few minutes to test when I first put the engine in and ut got real hot real fast under the hood, so I found a set of muffler heat shield tins and put them on it. I could probably fry an egg on the hood.

I'll try the foam and see what I can do about air flow from under the frame (replace the sheet metal with mesh) and see how that goes. I'll considering switching to a vanguard 16hp engine in this rig to see if it gets as hot under the hood after that. I have one here, that wouldn't be a big job for a test. It has 300 less hours than the command does... It should still have the power I need.