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LM 318 HTGR Starter Question

piper468

Contributing Member
I have Prestolite MDT-7021 and 7022 direct drive starters on my boat. (LM 318's) I recently purchased HTGR replacements from Rare Electrical but they don't engage the flywheel. I measured the throw on my old starter and its 1/2 inch more than the HTGR's. The distance from the face of the starter mount to the back of the flywheel is 2 inches. The HTGR starter travel is 1.5 inches Can you adjust the travel or do I send these back to Rare Electrical? I've already sent them an email but I probably won't hear back from them until next week. Thanks

Russ
 
I have Prestolite MDT-7021 and 7022 direct drive starters on my boat. (LM 318's) I recently purchased HTGR replacements from Rare Electrical but they don't engage the flywheel. I measured the throw on my old starter and its 1/2 inch more than the HTGR's. The distance from the face of the starter mount to the back of the flywheel is 2 inches. The HTGR starter travel is 1.5 inches Can you adjust the travel or do I send these back to Rare Electrical? I've already sent them an email but I probably won't hear back from them until next week. Thanks

Russ

Russ
I use them all the time. what is the Rare Electrical part number?
Here is part of an old post I did.

Part numbers are:
5248 for CCW starter rotation looking at if from the drive gear end
5222 CW starter rotation looking at if from the drive gear end

As the above keep in mind that the same starter is also for small blocks, BUT, the small block starter aims to the front of the engine and a big block starter aims to the rear of the engine. This makes a standard rotation 440 use a CW starter and a standard rotation 318 use a CCW starter.
You would not believe how many get this @#$^&^&$^# up.

Hope this helps

Dan
 
Dan,
I ordered the 5248 and the 3471 starters. The main issue is they don't engage the ring gear. They come up about 1/2 inch short. Any ideas?

Russ
 
Russ
Is this the starter you are having the issue with:

High speed starter 5248-1.jpg
I have used these without any issue. I modify the 318 aluminum bell housing to bolt to 440's so I can have the top mounted starter in ski boats. I use the 318 flywheel which makes it all the same as a 318 and this starter works great. Does the drive touch the flywheel when it is engaged but just grind or does it not even touch it at all?
There are 2 different tooth pitches these starters can get. The older 172 tooth and the newer 143 tooth( not used on marine but was in automotive which this starter is also used). You should have only 9 teeth on your drive gear, if it is 11( I think) then it is the wrong pitch.
Let me know if it hits the flywheel at all. I have never come across this, yet.
I just put one on an engine and it worked perfectly.
Dan
 
Yes that's the starter I have. It has 9 teeth on the drive gear and when I engage the starter it doesn't touch the ring gear at all no grinding noise just the bendix spinning freely. When I pull the bendix out all the way to its full travel it's 1.5"'s from the flange of the starter mount to the top of the drive gear. My flywheel on the boat is 1.75"'s form the bell housing flange to the aft face of the ring gear. If I'm correct with my math it's missing the flywheel by 1/4". My original starters Prestolite MDT-7021 and 7022 measure 2"'s total travel of the bendix gear. On their website Rare Electrical shows that these are direct replacements for the Prestolite ones. I'm truly baffled why they don't work. My boat is in Alaska and I live in Washington State so my access is limited. But I took really good measurements before I left. I'm going to call Rare Electrical tomorrow and hopefully I can talk with a Tech Services person about this issue. In the mean time could you take a few measurements for me. What is the distance form the starter mount face on your bell housing to the closer face on your flywheel? Just curious if I have something different.

Dan, Thanks for your help so far!

Russ
 
Russ

It sounds like the drive is not coming out properly due to a restriction in the sliding of the drive. It is almost like you have a left hand bendix on a right hand motor. Try this, the bendix should free wheel in the direction that the starter rotates and be harder to turn as it grabs the armature when rotated against the rotation direction. If you have the wrong Bendix then it will not work right.
I am not at the shop and will not be until next weekend. Guys at Rare have always been good to work with.

If you want I have about 1/2 dozen of the older starters in perfect condition I do not use. You can have a couple for the cost of shipping so you have some spares since you are so far away. They are just the stock ones.

Will check on dimensions next week. Let me know what the guys say. Contact at Rare Electrical is Tony. He can direct you to the right people.
 
Dan,

Both starters free wheel one way and have some resistance the other. I'm sure they're OK. I thought I would bolt them to a piece of wood and use a remote starter switch to run them. That way I can see if the bendix is coming out far enough to engage the ring gear. Thanks for offering the old starters. I'm really trying to get away from the old direct drive if I can. I've had the boat for 25 years and the old starters have always been an issue. The way my Uniflite is set up the Battery cables have to travel a total of twenty feet before they get back to the starters. The loss of current is substantial even with 2/0 cable. I know that these new HTGR starters are the way to go and I wish they had them back 20 years ago. Marine use of course. Next year I'm going to move my battery switches back behind the motors so the cable travel will be minimal. That's a big project though but I know it needs to be done. I was really amazed how light the new HTGR starters are in comparison to my old ones. I bet I could use the old Prestolites as an anchor if need be. I'll let you know what I find out tomorrow. Thanks again for your help on this.

Cheers

Russ
 
Russ, I think that we'd be hard pressed to see a Bendix drive type starter motor being OEM these days. All OEM are the HTGR/PMGR type motors...... be it I/Bs or I/Os.

There has to be a reasonable explanation as to why the drive gear is not engaging the ring gear!

Once you sort this out, you'll like the performance of the HTGR/PMGR motors!


.
 

Russ .................

Both starters free wheel one way and have some resistance the other.
The drive gears on the HTGR/PMGR motors use a sprague clutch affair.
They will free-wheel with the normal rotation direction, but will lock up completely against the driven direction.

I'm sure they're OK. I thought I would bolt them to a piece of wood and use a remote starter switch to run them. That way I can see if the bendix is coming out far enough to engage the ring gear.
The HTGR/PMGR motor pinion gear is kicked out via solenoid lever action. No Bendix drive!
(Bendix drive pinion gears are thrown out by quick armature torque ... no lever assist)

You may want to disconnect the commutator lead from the solenoid, and try to exite the solenoid's "S" terminal only.
This will throw the pinion gear out without spinning the armature.
You can then take your measurements safely.


The way my Uniflite is set up the Battery cables have to travel a total of twenty feet before they get back to the starters. The loss of current is substantial even with 2/0 cable.
I agree with Jeff....... if you can, find a way to lesson this distance.

I know that these new HTGR starters are the way to go and I wish they had them back 20 years ago.
Chrysler auto used a HTGR motor in the late 50s. If you can remember any of these, they always had a different sound when starting.

Next year I'm going to move my battery switches back behind the motors so the cable travel will be minimal. That's a big project though but I know it needs to be done.
You may want to re-think that.
IMO.... our MBSS's should be easily accessible outside of the Engine Bay.
Imagine an electrical issue or fire, and trying to open a smoke filled engine hatch to access your MBSSs!

I was really amazed how light the new HTGR starters are in comparison to my old ones.
Yes... and with the gear reduction, the armature spins approx 3 x's faster than the old Non-Reduction units, they will typically spin the crankshaft faster and will use less amps doing it.
 
Rick I wish we would stay on the subject of this thread. I know you guys have a lot of knowledge but you don't have all the info correct.

1. The two starters I have in hand are both OSGR ( Off Set Gear Reduction ) and they both have a bendix drive. See this link---

http://www.autocosmos.co.za/documents/Starter_and_Alternator_-_Information.pdf

2. I already did an electrical bench test, only to verify that the starter drive gear was coming out. Then I took the measurements on a bench without power.

3. I think if you read my earlier post I already said that I need to shorten my battery cable length. A little history. I've had this boat since 1989. 1972 27' Uniflite. Solid Hull. Uniflite put the battery switches underneath the steps going into the lower cabin. I know and have known for years that I need to move those switches to a more practical and safe position. Mostly because my battery cable run needs to be a lot shorter. When I said that I was going to move those behind the motors I didn't say that they would be in the engine room or anywhere by the motors. Earlier when I said this was a big job it was because I'm going to make a battery switch compartment in my floor just aft of the engines.

4. Read the sentence right after I said "I know that these new HTGR starters are the way to go and I wish they had them back 20 years ago" ---------Marine Use of Course. I am aware that gear reduction starters have been around a while but I know that they didn't have them for marine use back then.

Hey guys I've sat in the background for years on this site. I've learned a lot from each of you and hope I can still learn some more. I don't like to type never did. One thing about this forum that gets old for me is when we don't stay on the subject of the thread. We go off on these tangents. I have a specific issue with the starters that I purchased and with everyone's help I hope I can resolve it.

Today I spoke with Rare Electrical again. Apparently they don't have a Tech Department and that's no help to me. I did email them some pictures of the starter drive gear extended with a ruler behind it. They are sending me an RMA number so I can return the ones I have. This still doesn't solve the issue I have. And what about the next guy that wants to order the same starter for his boat and it doesn't work. Their website shows that these are direct replacements for the Prestolite MDT-7021 and 7022 starters. If their starters work in some applications but not others what in the hay is going on. That's what I need to know. What is different with my configuration? OEM Bell Housing, OEM Starters, OEM Flywheel. Help anyone?

Thanks
Russ
 
I looked at the Autocosmos web site that you linked us to. I belive that they're using the term "Bendix" in a broad sense... perhaps incorrectly.

A Bendix drive is thrown out into the ring gear by the steep spiral splined shaft upon quick armature/shaft rotation enertia!
This is often why a low voltage scenario may cause a Bendix drive motor to not engage.

Note the absence of a solenoid lever arm.

images


Here's a view of the Bendix drive and the steep spiral cut splines.
images

The Bendix company also provides sprague type solenoid lever action pinion gear units such as what the web site shows.
Perhaps this is where the confusion lies.

This is a solenoid lever action starter motor.
Note the solenoid lever action that kicks the pinion gear into the flywheel ring gear.

images



Any of the soleniod lever types can be either direct or gear reduction.
You may find a Bendix style in a gear reduction motor, although I'm not familiar with any.



I'll bow out of your thread since you feel as though I've deviated from the topic and that I did not get all of the info correctly.


Good luck with the issue.



.
 
Thanks Rick for the clarification of the bendix drive. I don't want to insult you so I'm sorry if I did. I could always use your experience to help figure out the issue. I'm a tad bit upset because the people at Rare Electric are giving me the run around. I'm going to start a new thread with detailed pictures so maybe someone out their can figure it out.

Thanks
Russ
 
Have you ever changed the flywheels? are there different offsets available? Good luck getting this resolved and keep us posted.

will
 
I think I found the issue see the POST below labeled [h=2]Gear Reduction Starter Replacement LM318's[/h]Cheers

Russell
 
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