AFC boost line...

[Diesel]

Earlier this week my pre-heater grid remained on and overheated. Fortunately it only remained on for about an hour, so my batteries weren't drained, but things evidently got hot enough that the boost line which goes from the side of the intake manifold to the rear of the AFC housing melted off at the manifold. I immediately unplugged one wire from each one of the pair of solenoids/relays (whatever they are) mounted on the left inner fenderwell and am still running without a pre-heater, and will have to buy a new pair of solenoids soon I suppose.



Main question: When removing the factory boost line to replace it with a temporary makeshift piece so as to get boost enrichment, I noticed that the brass fitting that threads into the rear of the AFC housing has a very small hole - almost like a restrictor of some sort. Nothing goes through that line except boost pressure, so why the small orifice?



Second question: Other than the obvious melted boots of the two main pre-heater wires, is there anything else I should look for?



Third question: Is there any harm done by running without a pre-heater? Other than a few seconds of white smoke that is...



Thanks in advance...



Steve

 

[Diesel]

I sure could use an answer here fellas...



Thanks



Steve

 

[illflem]

Steve, the small hole is to slow the flow down so the wastegate doesn't cycle open/shut rapidly.

2) probably just the wires.

3) you better have the grid heaters hooked up or chances are if it gets below 10° your trucks batteries will die before it starts. If it doesn't get much below 25° you will be fine but the extra cranking will wear your starter and batteries faster.

 

[Diesel]

Originally posted by illflem Steve, the small hole is to slow the flow down so the wastegate doesn't cycle open/shut rapidly.

2) probably just the wires.

3) you better have the grid heaters hooked up or chances are if it gets below 10° your trucks batteries will die before it starts. If it doesn't get much below 25° you will be fine but the extra cranking will wear your starter and batteries faster.

Thank you Sir - I was beginning to wonder if I have bad breath or something... or maybe someone told on me about the Chevy parts in the garage...



Anyway, the stock 12cm wastegated housing has been sitting on the shelf for about 5 years now, so I guess I can set the small orifice fitting next to it.



Yes, the wires are all I see - wasn't sure if there's something I don't see that someone whose heater grid went south on them might know about. I couldn't guess how much money I've saved just by reading this site...



As for the starting, it always starts in half a second. I've never had to do any more than just 'bump' the ignition start position, even in the deep cold.



Love my Cummins



Thanks again...



Steve

 

[Joseph Donnelly]

Actually the restriction is on the other side from the line for the wastegate. It moderates the speed the AFC responds to boost changes. A bigger hole may increase smoke, but you can try it.



Check the aluminum parts for possible warping from the heat, or gaskets for damage. Just pull off the air intake and look at it and its gasket. If OK, the gasket between the aluminum plenum cover and the head is probably OK too.

 

[Diesel]

Originally posted by Joseph Donnelly Actually the restriction is on the other side from the line for the wastegate. It moderates the speed the AFC responds to boost changes. A bigger hole may increase smoke, but you can try it.



Check the aluminum parts for possible warping from the heat, or gaskets for damage. Just pull off the air intake and look at it and its gasket. If OK, the gasket between the aluminum plenum cover and the head is probably OK too.

Okay thanks, I'll pull it apart this weekend.



Joe, I wonder if there would be any advantage in leaving the fitting with the small orifice in place... since I'm using the 16 sq/cm non-wastegated housing and the wastegate boost line has been removed as well, of course.



I'm currently using a makeshift piece so as to get boost enrichment, and I'm not noticing any extra smoke... but then I have one of your #10's in her...



Anyway, thanks for the reply.



Steve

 

[GAmes]

Diesel, I grew up just down the road in Dallas. There is no such thing as "deep cold" in the Willamette valley. Deezul1 is from Falls City... ..... small world. Any way, you are lucky, when my heater grid crapped out it cooked both batteries and fried the alternater. Of course the DC warranty didn't cover the batteries.

 

[Diesel]

Originally posted by GAmes Diesel, I grew up just down the road in Dallas. There is no such thing as "deep cold" in the Willamette valley. Deezul1 is from Falls City... ..... small world. Any way, you are lucky, when my heater grid crapped out it cooked both batteries and fried the alternater. Of course the DC warranty didn't cover the batteries.

Come on now, we actually got some snow this last weekend - real honest to goodness snow... I was an over-the-road driver for 15 years and when I took vacation time, what would I do but hit the road! I actually got antsy just sitting - I had to move; hard to explain. Anyway, the coldest my truck has seen is in the 20's below, so I guess I shouldn't have said 'deep' cold, but she fired up without complaint.



My brother-in-law's heater grid fried last year - it didn't fry the alternator but it ate both batteries and just about everything near it. I think he wound up paying out in the neighborhood of $600 all told... and that's a bad neighborhood if you ask me. Now his shutoff solenoid is sticking and I wonder if it's related. His truck fails to start sometimes (occasionally) until he lifts the plunger up, and yes, I'm relating all the pertinent information I can find off this site to him, hoping to find a cheaper cure than a new solenoid.



Well, nice talking to a fellow webfoot and y'all take care down there.



Steve

 

[fest3er]

One of my heater relays failed and stuck on, melted the little booties, and melted the AFC hose. Dealer replaced the relay set and said 'everything' else was OK, but when I picked it up, it had 0-60 times measured in hours; had to replace the AFC boost line. Both batteries were totally drained, but they charged up OK after.

I just replaced them after 4+ years of use.



Since then, I again noticed the headlights and dash lights flickering at night, so I replaced the OEM heater relays with a set from Stancor (see http://home.adelphia.net/~npmrphy/relay.pdf).

These relays turn off with a satisfying 'thunk'.



So, as a reminder, since this is the time of year when folks are more likely to be driving in darkness, pay attention to your headlights and dash lights whilst driving. If you notice them flickering (the lights dim a little for 10s to 100s of milliseconds but do not go completely out) whilst driving over rough-ish roads, yet the voltmeter remains steady, you may well have a relay failing, which could well lead to a meltdown.



Fest3er