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Cranking speed, direct-drive vs gear reduction starters
by
Luckypabst
on 04 Feb, 2014 18:36
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Does anyone know the advertised, loaded cranking speed for the various starters?
Specifically the Mk1 direct-drive starter vs a gear reduction starter from an automatic Passat (pretty sure that was the application).
My OEM starter crapped out at the same time that I installed a new, aftermarket cylinder head about a year ago. On the advice of a friend at the local starter shop, I installed the gear-reduction starter. The car has never started as easily since and I blamed the new head. This past weekend at ~10 degrees F, it wouldn't start at all. Interestingly it fired right off by bump-starting in 2nd so I know that it'll start easily with a little more cranking speed. Glow plugs are fine, etc. This is either related to starting speed or the head.
Thanks
Chris
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#1
by
TylerDurden
on 04 Feb, 2014 18:51
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Got compression numbers?
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#2
by
745 turbogreasel
on 04 Feb, 2014 18:59
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I find regardless of type, cheap aftermarket starters are nowhere near as good as OE or quality starters.
Case in point the $80 new starter on my Suburban blew the housing apart after about 6 months.
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#3
by
TimpanogosSlim
on 04 Feb, 2014 23:04
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I find regardless of type, cheap aftermarket starters are nowhere near as good as OE or quality starters.
Case in point the $80 new starter on my Suburban blew the housing apart after about 6 months.
And the rebuilt OE starter on my parents Aerostar failed in a week.
Anyway, he didn't state clearly whether his new starter is one he pulled out of an automatic mk4 (or corresponding passat - i forget the number).
and yeah, compression numbers.
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#4
by
Luckypabst
on 04 Feb, 2014 23:10
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It was a parts store replacement starter. I'm not looking for a diagnosis, just cranking speeds of various starters.
Chris
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#5
by
Toby
on 05 Feb, 2014 00:32
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My experience across board is that gear drive starters crank much faster in any application that I have encountered. I put a new Denso gear drive starter on my syster-in-laws 92 F350 last fall. It had a series of direct drive starters over the years and the thing never started worth a crap in the 12 years that she has owned it. New batteries, new factory cables, new solenoids and it would not start reliably, ever. Now it pops of so fast its kind of un-nerving. Before you realize that it is cranking, it has started. She thinks I walk on water. She had previously spent about $2500 trying to get it to start.
That being said this was a quality name brand starter. Everything that I have ever seen that was chinese that had moving parts was crap. Without exception.
I would try a name brand gear drive starter and see whats happens. Even a used one, as long as its factory. I have had such problems with chinese junk starters and parts that I will fix a bad factory on if at all possible and save the china junk for a last resort. Things like 5 brand new bad starter drives from five different brands but all from china and they wouldn't crank the truck. I went to Ford and spent 4 times the money for the drive and it was still working fine 100,000 miles later.
I would suspect if the motor popped right off on your bump start that your problem is cranking speed, not compression. If you had to drag it for a block, that may be another matter.
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#6
by
TylerDurden
on 05 Feb, 2014 04:02
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Cranking speed and compression are directly related... Low compression engines will leak down fast enough to not fire, if the cranking speed is slow. High compression engines will light-off on the first cylinder reaching TDC, practically regardless of cranking speed.
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#7
by
theman53
on 05 Feb, 2014 05:06
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I honestly think they will crank the same rated speed, but the gear reduction takes a load better than the direct drive so it doesn't bog down as much under load. Meaning real world the gear reduction will crank faster in use.
That being said and I know you have stated a couple times you don't want diagnosis, but the main question I have is the starter bushing...if it wasn't replaced that can cause very bad cranking and ruin a starter in 2 weeks *I know from experience* So let me know that and how you lubed it as I have a tip to make the bushing self lubing. The auto Passat I don't think has a gear to go into the trans so the bushing is not the issue. But the old voltage drop test that BYM put in the FAQ helps a ton. I have replaced all the battery cables on all my older VW's with new and heavier gauge stuff because they just aren't cutting it after 30 years.
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#8
by
Luckypabst
on 05 Feb, 2014 09:17
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Thanks y'all. My starter shop buddy said the cranking speed should be the same. He also said I probably have too much compression with a new head.
Anyway, it's strange that the engine goes from firing nearly immediately under any condition, then requiring extended cranking even when warm. The two variables are the new head and starter, both replaced at the same time.
Chris
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#9
by
Mark(The Miser)UK
on 05 Feb, 2014 10:03
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Thanks y'all. My starter shop buddy said the cranking speed should be the same. He also said I probably have too much compression with a new head.
Anyway, it's strange that the engine goes from firing nearly immediately under any condition, then requiring extended cranking even when warm. The two variables are the new head and starter, both replaced at the same time.
Chris
Surely newness of head won't affect the compression, unless different swirl chamber size. Newly polished chamber, may retain more heat in the compressed air, but that can only be good.
Have you installed a thicker headgasket perhaps?
Were the rings done, at the same time as a 'might as well' after thought, often promoted here?
Same for new shells...
'Improvements' on the timing setting can also influence starting ease.
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#10
by
theman53
on 05 Feb, 2014 15:23
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Well the other variable is that with a new head is new timing.
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#11
by
Luckypabst
on 05 Feb, 2014 17:07
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Does anyone know the advertised, loaded cranking speed for the various starters?
It sounds like that's a no.
You guys have really lost sight of the question. Nothing below the engine deck changed. The head gasket is correct for piston protrusion. Pump timing is spot on and exactly the same as before. Glow plugs are new and confirmed to work. Tire pressure hasn't changed. My radio still only works on AM. I still get confused for some drug smuggling hippie. The sun still sets in the west.
Chris
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#12
by
fatmobile
on 05 Feb, 2014 17:13
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From my experience, the direct drive starter spins faster,... in the summer.
The gear drive will sustain a higher RPM for longer in the very cold, whereas the direct drive is a little faster at first but drops off.
Nothing official/advertised so personal experience might not count.
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#13
by
RabbitJockey
on 05 Feb, 2014 17:39
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i have used both extensively over the years... i would agree with what fatmobile has said... i never noticed much of a difference other than how they sounded... and my cars always had fresh starter bushings as well. but if it means anything, when id replace any in the future, i'll be buying the gear reduction models.
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#14
by
theman53
on 05 Feb, 2014 19:25
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I can not try to help, but I thought I said that they should spin the same RPM???
If you didn't adjust the pump after putting a new timing belt on with the head I would guess that is your issue or part of it.