8.3 mechanical delayed start

[tbostrom]

Hi Guys,
We own a ‘95 HR with a 8.3 mechanical and MD3060 transmission. Over time it has been increasingly hard to start. When the key is turned on and the engine pre-heat light goes out, it still will not turn over. After 25 - 30 seconds I hear the contacts close in the Allison relay box located under the dash on the drivers side, and then it starts no problem. After it has started, it can be restarted no problem with only a slight delay. Yesterday it took 50 seconds before the relays kick in.Freightliner has gone thru the chassis and cannot identify the problem Which seems weird.
Does anybody out there have any ideas?
Appreciate any suggestions.

[deandec]

I have the same equipment on a Gillig Bus chassis.

My rig has both an ignition solenoid and a starter solenoid.

If your schematics show the same configuration, my WAG would be that your ignition solenoid is not engaging immediately with the key..

When my ignition solenoid failed, the transmission pad would not light up and I had a no crank problem.

Perhaps either the ignition solenoid is weak or has a poor ground (my situation).

[tbostrom]

Originally Posted by deandec

I have the same equipment on a Gillig Bus chassis.

My rig has both an ignition solenoid and a starter solenoid.

If your schematics show the same configuration, my WAG would be that your ignition solenoid is not engaging immediately with the key..

When my ignition solenoid failed, the transmission pad would not light up and I had a no crank problem.

Perhaps either the ignition solenoid is weak or has a poor ground (my situation).

Thanks deandec
I’ll check the connections and/or replace the starter solenoid and see if that the fix.
Will let you know.

[tbostrom]

Originally Posted by deandec

I have the same equipment on a Gillig Bus chassis.

My rig has both an ignition solenoid and a starter solenoid.

If your schematics show the same configuration, my WAG would be that your ignition solenoid is not engaging immediately with the key..

When my ignition solenoid failed, the transmission pad would not light up and I had a no crank problem.

Perhaps either the ignition solenoid is weak or has a poor ground (my situation).

Hi Dean,
Checked all the connections and replaced the ignition solenoid and still no improvement. I’m going back to Freightliner and try and get some answers.
Thanks for your suggestions tho as it only cost me $34.00.

[BIGBADDOG]

Check your batteries and all your connections. Sounds like the relay is getting low voltage because of the intake heater and the voltage is coming back up enough after 30 / 60 seconds to energize the relay. Mike

[tbostrom]

Originally Posted by BIGBADDOG

Check your batteries and all your connections. Sounds like the relay is getting low voltage because of the intake heater and the voltage is coming back up enough after 30 / 60 seconds to energize the relay. Mike

Thanks for the tip Mike.
I thought the connections were good but will double check and see if that rectifies the problem. Your suggestion makes perfect sense. Ted.

[deandec]

Does the delay occur when you activate the battery boost switch?

[tbostrom]

Yes, there is still a delay even when I use the battery boost switch. It’s odd cause once it starts, I can restart with only a minor delay like 2 seconds, even if the engine is cold. But if I wait 15 minutes and try to restart it will take 20 seconds or so for the relays to activate.

[deandec]

The delay sounds like a fuel preheat cycle. I am not familiar with that on my engine, except on the generator start sequence.

On my dash there is a "wait to start" lighted warning if the air temps are below @ 40F degrees.

To overcome that, I think I need to turn on the ignition but not try to crank the engine until the light turns off.

Perhaps you have something similar for preheat that causes the delay until the engine thinks it is ready to start?

FWIW, my engine cranks immediately.

[tbostrom]

Originally Posted by deandec

The delay sounds like a fuel preheat cycle. I am not familiar with that on my engine, except on the generator start sequence.

On my dash there is a "wait to start" lighted warning if the air temps are below @ 40F degrees.

To overcome that, I think I need to turn on the ignition but not try to crank the engine until the light turns off.

Perhaps you have something similar for preheat that causes the delay until the engine thinks it is ready to start?

FWIW, my engine cranks immediately.

Yes, My original thoughts were that there was something wrong with the engine pre-heat system but I’m not sure were to look for a potential cause of the delay.
I had Freightliner look at it and spent $1800.00 to diagnose the problem with no results.....OUCH!

[deandec]

I think I have the grid heater vs the flame start heater.

Here is a web page for the flame start, but it reads like the same procedure as the grid heater.

https://www.equipmanuals.com/blog/fl...-c8-3-engines/

Another diesel starting summary:

"There are several different options for starting diesels, and the best option for any particular engine depends on the design of the engine and any 'starting aids' it has. For a particular vehicle, your best option is to refer to the owner's manual for starting in various (hot/cold) conditions. If you have problems starting, it may be that the starting aids aren't working properly."


Perhaps your grid heater is blocking the start process.

Or, perhaps your chassis battery is not passing enough power to the heater as a previous poster suggested.

I am just flinging out possibilities maybe something will connect.

[tbostrom]

Originally Posted by deandec

I think I have the grid heater vs the flame start heater.

Here is a web page for the flame start, but it reads like the same procedure as the grid heater.

https://www.equipmanuals.com/blog/fl...-c8-3-engines/

Another diesel starting summary:

"There are several different options for starting diesels, and the best option for any particular engine depends on the design of the engine and any 'starting aids' it has. For a particular vehicle, your best option is to refer to the owner's manual for starting in various (hot/cold) conditions. If you have problems starting, it may be that the starting aids aren't working properly."


Perhaps your grid heater is blocking the start process.

Or, perhaps your chassis battery is not passing enough power to the heater as a previous poster suggested.

I am just flinging out possibilities maybe something will connect.

Thanks for the info Dean. I’m going to research this when I get back home. We’re on a 3 week trip right now staying put for a week at a time.
This forum is great thanks to people like you.