Fire Perkins 4.108 Cold Start Option

[cburger]

I have been installing 1984 Perkins low line with the cold start feature in my boat. I have use the old wiring harness but not the panal, used the custom made panal that was installed in my boat as it was in much better shape than the one that came with the motor as part of the purchase. Any way today I was starting to sort out the ignition circuit for the preheat element at the air intake on the manifold and as Perkins ran two wires (Maybe 10 gauge) to the element and a ground off the other end of the element I was a bit confused (Lucas insanity). I want to fix a seperate push button switch to activate the heater so I was trying to figure out what the two wire deal was. With the intake cover off so I could view the element I was suprised to see that when either one of the wires touched to a positive lead the element started glowing bright red, and after maybe ten seconds I got maybe a three inch flame in the intake. Once the wire was disconnected flame goes out. The first question is is the flame in the chamber normal? The second question is why is Perkins running two hot wires to the element, if the answer is an amperage issue why not one large wire properly sized for the load?

[cburger]

Could sure use some answers to this question, don't want to start a fire in the engine room.

Thanks

[GordMay]

Fire in the cold-start reservoir is NOT normal.
See “Operating & Maintrenance” (to operate the cold start aid), page 32 etc.
Perkins Workshop Manual
➥ http://www.endeavourowners.com/dscsn...p%20Manual.pdf

[cburger]

Thanks Gord, I read the manual and it indicates that to avoid damage to the element it should not be energized while the lines are dry. Considering the fuel lines were not connected I hope no damage was caused. I only energized the circuit for 15 seconds and am assuming that residual fuel from the filter was being drawn into the mainifold and in fact being ignited, could smell diesel. I believe there was a thread here a while back where someone who was very familiar with the Perkins cold start feature refered to the operation as fire in the manifold. I will try and locate his post.

[lancelot9898]

I have the Perkins 4-108 without the cold start option and never had an issue with starting even in some cold temperatures. I sail for the most part on the northern/central Cheaspeake(March through November) and remember anchoring out one late November night with the temperatures dipping into the low 20's. However the cabin was heated so the engine never did get down to that temperature, but she started up fine even with that cold of temperature on the outside.

[cburger]

Thanks, I realize this but wish to understand the feature and have it working safely.

[hummingway]

I wanted the cold start with my 4.154 - long crank in cold weather. I didn't have the ignition described by the Perkins manual for the cold start so I ran a 10 gauge wire to a selenoid from the motor and ran the activator wire from the Acc on the ignition to a push button to the selenoid.

In descriptions of this system others have made I'd read that some will begin cranking after a 20 count holding the push button, before releasing the button. With the system I have this produces too much draw for the battery so I release the button before cranking and it works.

[cburger]

After some snooping around on the internet I found this Perkins engine manual that I had never seen before, it has greater detail on the cold start feature and does indicate that upon turning the starter that the vaporized fuel in the intake manifild should burst into flame, (page 27). Still trying to figure the wiring issues.

http://users.firenet.uk.com/stewartbray/perkins4108.pdf

[hummingway]

I believe that's the idea. I see smoke from it at the air intake. When you crank the fire is sucked into the cylinders.