6.7 starter in a 7.3

I was going to take some pics. It’s simple. Remove the philips screw that goes from the body into the nose cone. Then remove the nut that holds the wire to the motor off the solenoid (the other big post on the solenoid). Then remove the two long bolts that hold the motor to the starter body and nose cone. Now you can remove the motor. Be careful not to pull the motor out of the brushes in the base. If that happens it’s no big deal, just a pain to get them reset. Once the motor is separate, there is another philips screw you have to remove. That holds the nose cone to the body with the solenoid. Now you can remove the the nose cone. A gear and the actuating gear will stay in the nose cone. I knocked them out with a hammer and used the gear and bearings out of the 6.7 because the internal bearing was different sized. The big bearing that goes into the nose cone was still the same size. Then reverse.

It seems like a lot, but it’s simple. I’ve never had my hands in a starter. Just gotta watch how it comes apart and reverse the process.

DENSO starter still has more punch for sure.

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I just did this swap today....huge difference in cranking power. I originally put the SD 7.3 starter in my OBS back in the day. The SD starter started to have a slow death. I would crank fast then it'll slow down. Batteries and cables are fine. So before it totally dies, I put the 6.7 starter in.

Yes, the nose cone needs to be swapped over. You have to take the starter to do the swap but it's worth it.

There are plenty of threads on how to swap nose cones.

I bought a new 6.7 starter from my Ford source.

The old SD 7.3 starter is on the left and the 6.7 one on the right. The nose cone swap wasn't done yet. But you get the idea.

I highly recommend this.







Billy T.
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hucorey said:

DENSO starter still has more punch for sure.

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Yuuup.

6 years on mine and it even fell out twice.

Thanks for reviving this. I've limped along with the factory mitsu unit but it's had enough. I'd have to find a core for a denso unit to make this happen. Does the 6.7 have that much more power than a new SD denso?

Yes, just do it and don't look back.

Billy T.
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I'm very curious to see how long these last.

Would you think it would have a shorter life span in a 7.3 as opposed to a 6.7? Curious as to why if that's what you are asking. 6.7's have been out since 2011 so I'd say there is a fair amount of data floating about as to their starter life. Application should really be irrelevant unless the starter is next to a set of headers or an exhaust without adequate heat shielding?

What's weird is that the 7.3 starters are between 3.8 and 4.0 KW and the 6.7 starter is only 3.0, the 6.4 starter is 3.1 KW. Curious why the 6.7 starter is sounding like it works better?

I Would think a 7.3 is far more harder to crank over then a 6.7. Hence why the DENSO units are very robust

justinlogue5_0 said:

What's weird is that the 7.3 starters are between 3.8 and 4.0 KW and the 6.7 starter is only 3.0, the 6.4 starter is 3.1 KW. Curious why the 6.7 starter is sounding like it works better?

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Exactly. Many people fail to research the kw output of all the starters. Cleaning the connections once in a while, newer battery cables, and good batteries will keep a 7.3 cranking over fast.

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I would like to see a comparison of a 6.7 hybrid starter vs a new 7.3 starter....

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justinlogue5_0 said:

What's weird is that the 7.3 starters are between 3.8 and 4.0 KW and the 6.7 starter is only 3.0, the 6.4 starter is 3.1 KW. Curious why the 6.7 starter is sounding like it works better?

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hucorey said:

Exactly. Many people fail to research the kw output of all the starters. Cleaning the connections once in a while, newer battery cables, and good batteries will keep a 7.3 cranking over fast.

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Let's see what I remember from my motors class.....DC motors are rated in kW instead of HP which really means nothing here unless you know the rest of the specs (nameplate). The armature and field winding are bigger on the 6.7 starter, just going off of the video. If the wiring of field winding is larger in size, it'll have less resistance. Therefore, by reducing field current, the speed also increase which leads to increase in mechanical power output.

I built my own battery cables out of welding cable. This is the wire size I used:
Positive
- battery to starter -> 4/0
- battery to battery -> 3/0
- battery to solenoid -> #1 (I think)

Negative
- both batteries -> 3/0

I switched over to military style battery terminals. When the glow plugs activated, my battery voltage was 10.9v with the old cables. After I built my cables, the battery voltage is 11.4-11.5 with the glow plugs activated. The battery voltage is read through the factory AIC while I wait for the GPs to heat up.

I know for a fact that the 6.7 starter cranks way faster than the SD 7.3 starter vs the 7.3 OBS starter.

Billy T.
[email protected]

How does the 6.7 starter compare to a genuine Denso unit? Working on a truck for a friend and the original starter is way past due for replacement. I can get her either one for about the same price.

gnxtc2 said:

Let's see what I remember from my motors class.....DC motors are rated in kW instead of HP which really means nothing here unless you know the rest of the specs (nameplate). The armature and field winding are bigger on the 6.7 starter, just going off of the video. If the wiring of field winding is larger in size, it'll have less resistance. Therefore, by reducing field current, the speed also increase which leads to increase in mechanical power output.

I built my own battery cables out of welding cable. This is the wire size I used:
Positive
- battery to starter -> 4/0
- battery to battery -> 3/0
- battery to solenoid -> #1 (I think)

Negative
- both batteries -> 3/0

I switched over to military style battery terminals. When the glow plugs activated, my battery voltage was 10.9v with the old cables. After I built my cables, the battery voltage is 11.4-11.5 with the glow plugs activated. The battery voltage is read through the factory AIC while I wait for the GPs to heat up.

I know for a fact that the 6.7 starter cranks way faster than the SD 7.3 starter vs the 7.3 OBS starter.

Billy T.
[email protected]

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That should be heavy enough to last a while. Lol

live life full throttle

It’s not the 6.7 but just put the Denso starter in from CNC.. why did I wait so long?? It rips! I was a cheapazz for long enough!