C10 Suburban Cummins - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MONTE · 03-14-2018, 03:49 PM

I got a 12 valve for my next project and I have a few questions for you guys. Donor engine is from a 1989 dodge. It was missing the vacuum pump/power steering. Went out to the junkyard and found one but it don’t work. I also found a crack on the housing unit. Would I need to replace it?

**Dieselwrencher** · 03-14-2018, 11:01 PM

Yes, I'd say replace that gear housing or have it welded properly. Those early 1st gens had a diaphragm type vacuum pump and the whole assembly is shorter than the later vane type vac pump setups. You can get the later vane style like you have to work with some mods to the throttle bracket. I'd rather have the later set up anyway.

MONTE · 03-14-2018, 11:35 PM

Thanks for the info. Hopefully I can get the correct 1 or get my refund for the pump.

MONTE · 03-16-2018, 09:20 AM

This was the original idea for my project.

MONTE · 03-16-2018, 09:26 AM

more pics

**Dieselwrencher** · 03-19-2018, 07:16 PM

Monte, very cool! That looks like a pretty clean truck. It also appears to be a Longhorn from what I can see from the pics. Do you plan to use that 727? If so you better try to get rear end gears near 3.08 or so.

MONTE · 03-19-2018, 07:22 PM

Im going with the automatic for now until I find a good manual transmission. The truck is a longhorn, it's in great condition.

**Dieselwrencher** · 03-19-2018, 07:38 PM

If you can find a D60 with 3.54 gears from one of these trucks, that would help. Your truck probably has 4.10s unless it was a big block truck.

MONTE · 03-20-2018, 12:12 AM

My truck is a big block 402 8 lug, I need to look and see what it has.

MONTE · 03-24-2018, 10:52 AM

Cooler heater exchanger/converter oil cooler

Where do I find a replacement cooler or do I need it ?
What setup are you guys using?
Would I need to replace the metal line or can I use rubber hoses for the coolant?
They are all rusted.

**Dieselwrencher** · 03-26-2018, 10:21 PM

That is the torque converter heat exchanger. On a Texas truck with a 727 I'd just toss it and put a good after market cooler in front of the radiator.

*Peanutbutter* · 03-27-2018, 01:46 AM

When I go down this road again I will put a block off plate on the gear housing and belt drive a common ps pump and go hydraboost. The marriage vacuum pump and ps pump can be a real pain if you get a bad shaft and seal on the ps pump. As long as you have the gear housing off make sure you put a fix on the killer dowl pin or it may destroy the whole motor. I was lucky, dowl pin fell down and instead of going between the two gears it got caught between the gear and tin cover, when I pulled the timing cover it looked like you had shot it with a 45 ACP from the inside out. Could'nt figure out where all the oil was coming from.

MONTE · 03-29-2018, 06:04 PM

Thanks for all the information guys. First time working on diesels for me.
Got a few parts today:
Gear housing
Expansion plugs
Water inlet seal
Water pump
Changing all the gaskets other than manifold and head.
Waiting on the Killer dowel pin to come in.

**Dieselwrencher** · 03-29-2018, 07:02 PM

Quote:

Originally Posted by MONTE

Thanks for all the information guys. First time working on diesels for me.
Got a few parts today:
Gear housing
Expansion plugs
Water inlet seal
Water pump
Changing all the gaskets other than manifold and head.
Waiting on the Killer dowel pin to come in.

Buying those parts from Mopar sounds pricey. Make sure you replace the oil cooler gaskets. I'd go ahead and do the cooler too if it has a lot of miles on it. Those early ones are known to leak and cause headaches. Make sure if your crankshaft has a groove worn in it that you get a seal with a wear sleeve other wise you will be having leaks again. That goes with the rear main seal too.

MONTE · 03-30-2018, 12:09 AM

I'll look into the oil cooler next.
Looks like a reman one will run about $200-$300.
Should I apply any type of permatex with the expansion plugs or just press them in?

**Dieselwrencher** · 03-29-2018, 06:59 PM

Quote:

Originally Posted by Peanutbutter

When I go down this road again I will put a block off plate on the gear housing and belt drive a common ps pump and go hydraboost. The marriage vacuum pump and ps pump can be a real pain if you get a bad shaft and seal on the ps pump. As long as you have the gear housing off make sure you put a fix on the killer dowl pin or it may destroy the whole motor. I was lucky, dowl pin fell down and instead of going between the two gears it got caught between the gear and tin cover, when I pulled the timing cover it looked like you had shot it with a 45 ACP from the inside out. Could'nt figure out where all the oil was coming from.

The power steering pumps have a drive coupler that is pressed on the pump shaft. That is a wear item and can be purchased with a new or reman pump. I can't tell you how many of these vac/ps pumps I've resealed and have no issues with them. I have had some severly worn ones I've had to source odd parts for but I still wouldn't hang a different pump off the side and run another belt to drive it. You can run hydroboost with a non hydroboost pump. You just have to either t the return or add a return to your reservoir on the pump.

**Dieselwrencher** · 03-30-2018, 05:13 PM

Which expansion plugs?

MONTE · 03-30-2018, 06:33 PM

Core plugs/freeze plugs.

**Dieselwrencher** · 03-30-2018, 10:45 PM

Red lock tite is what I use but usually I put in billet ones. You could use permatex rated for coolant though.

MONTE · 03-31-2018, 09:52 PM

Got the KDP today.

MONTE · 01-15-2019, 11:31 PM

Finally moving on the Cummins.
Found a Getrag transmission to go with it.
Got it running on a stand after a few rounds.
Was going to put it in a suburban I found in Portland, Oregon but the guy backed out. Saved me a 2400 mile roadtrip. So the search continues for a c20 suburban.
Injectors keep leaking from the top bolt. I’m going to remove the injectors/clean and torque back to specs, hopefully that fixes the leak.
I’ll try to post a video of it running.
This is what I’ve done:
KDP fixed
New front housing
New vacuum pump
Water pump
Gasket replacements
Thermostat
Crush washers
Oil line for vacuum pump
Throttle rod
Just ordered the fuel pin and 3200 spring from the hungry diesel.

**Dieselwrencher** · 01-16-2019, 07:52 PM

Are you sure the return bolts are leaking? Fuel can travel up the body from the nozzle and come out around the retaining nut and make it look like the return line is leaking.

MONTE · 01-16-2019, 11:13 PM

I don't think it's the return line. Removed all the injectors today reinstalled them. Looks like that fixed the problem for 3 of them. I can see bubbles around the retaining nut. I torqued them back to 44. I might take it another pound or 2. Hopefully that will fix that issue.

**Dieselwrencher** · 01-17-2019, 08:32 PM

The problem isn't the retaining nut torque. Your nozzles are leaking past the threads where the nozzle nut screws on to the body. I'm guessing by the looks of the paint on the body these are used or original to the engine?

Vintage Windmills · 01-19-2019, 11:36 AM

Cool project and nice longhorn! Are you looking for a suburban in general or one to put the cummins in instead of the longhorn?

Are you going to check your head for cracks? Some of the non IC 6BT's have them.

03-14-2018, 03:49 PM	#1
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	C10 Suburban Cummins I got a 12 valve for my next project and I have a few questions for you guys. Donor engine is from a 1989 dodge. It was missing the vacuum pump/power steering. Went out to the junkyard and found one but it don’t work. I also found a crack on the housing unit. Would I need to replace it? Attached Images Last edited by MONTE; 08-20-2021 at 11:07 PM.

03-14-2018, 11:01 PM	#2
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve Yes, I'd say replace that gear housing or have it welded properly. Those early 1st gens had a diaphragm type vacuum pump and the whole assembly is shorter than the later vane type vac pump setups. You can get the later vane style like you have to work with some mods to the throttle bracket. I'd rather have the later set up anyway. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

03-14-2018, 11:35 PM	#3
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	C10 Suburban Cummins Thanks for the info. Hopefully I can get the correct 1 or get my refund for the pump. Last edited by MONTE; 08-20-2021 at 11:12 PM. Reason: need to change title

03-16-2018, 09:20 AM	#4
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	C10 Suburban Cummins This was the original idea for my project. Attached Images Last edited by MONTE; 08-20-2021 at 11:12 PM.

03-16-2018, 09:26 AM	#5
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	C10 Suburban Cummins more pics Attached Images Last edited by MONTE; 08-20-2021 at 11:13 PM.

03-19-2018, 07:16 PM	#6
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve Monte, very cool! That looks like a pretty clean truck. It also appears to be a Longhorn from what I can see from the pics. Do you plan to use that 727? If so you better try to get rear end gears near 3.08 or so. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

03-19-2018, 07:22 PM	#7
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	C10 Suburban Cummins Im going with the automatic for now until I find a good manual transmission. The truck is a longhorn, it's in great condition. Last edited by MONTE; 08-20-2021 at 11:13 PM.

03-19-2018, 07:38 PM	#8
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve If you can find a D60 with 3.54 gears from one of these trucks, that would help. Your truck probably has 4.10s unless it was a big block truck. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

03-20-2018, 12:12 AM	#9
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve My truck is a big block 402 8 lug, I need to look and see what it has.

03-24-2018, 10:52 AM	#10
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve Cooler heater exchanger/converter oil cooler Where do I find a replacement cooler or do I need it ? What setup are you guys using? Would I need to replace the metal line or can I use rubber hoses for the coolant? They are all rusted. Attached Images

03-26-2018, 10:21 PM	#11
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve That is the torque converter heat exchanger. On a Texas truck with a 727 I'd just toss it and put a good after market cooler in front of the radiator. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

03-27-2018, 01:46 AM	#12
Peanutbutter Account Suspended Join Date: Feb 2013 Location: Mesa, Colorado Posts: 450	Re: C20/cummins 12 valve When I go down this road again I will put a block off plate on the gear housing and belt drive a common ps pump and go hydraboost. The marriage vacuum pump and ps pump can be a real pain if you get a bad shaft and seal on the ps pump. As long as you have the gear housing off make sure you put a fix on the killer dowl pin or it may destroy the whole motor. I was lucky, dowl pin fell down and instead of going between the two gears it got caught between the gear and tin cover, when I pulled the timing cover it looked like you had shot it with a 45 ACP from the inside out. Could'nt figure out where all the oil was coming from.

03-29-2018, 06:04 PM	#13
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve Thanks for all the information guys. First time working on diesels for me. Got a few parts today: Gear housing Expansion plugs Water inlet seal Water pump Changing all the gaskets other than manifold and head. Waiting on the Killer dowel pin to come in. Attached Images

03-30-2018, 12:09 AM	#15
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve I'll look into the oil cooler next. Looks like a reman one will run about $200-$300. Should I apply any type of permatex with the expansion plugs or just press them in?

03-30-2018, 05:13 PM	#17
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve Which expansion plugs? __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*



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03-30-2018, 06:33 PM	#18
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve Core plugs/freeze plugs.

03-30-2018, 10:45 PM	#19
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve Red lock tite is what I use but usually I put in billet ones. You could use permatex rated for coolant though. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

03-31-2018, 09:52 PM	#20
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve Got the KDP today. Attached Images

01-15-2019, 11:31 PM	#21
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve Finally moving on the Cummins. Found a Getrag transmission to go with it. Got it running on a stand after a few rounds. Was going to put it in a suburban I found in Portland, Oregon but the guy backed out. Saved me a 2400 mile roadtrip. So the search continues for a c20 suburban. Injectors keep leaking from the top bolt. I’m going to remove the injectors/clean and torque back to specs, hopefully that fixes the leak. I’ll try to post a video of it running. This is what I’ve done: KDP fixed New front housing New vacuum pump Water pump Gasket replacements Thermostat Crush washers Oil line for vacuum pump Throttle rod Just ordered the fuel pin and 3200 spring from the hungry diesel. Attached Images Last edited by MONTE; 01-16-2019 at 01:33 AM.

01-16-2019, 07:52 PM	#22
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve Are you sure the return bolts are leaking? Fuel can travel up the body from the nozzle and come out around the retaining nut and make it look like the return line is leaking. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

01-16-2019, 11:13 PM	#23
MONTE Registered User Join Date: Oct 2005 Location: Donna, Texas Posts: 286	Re: C20/cummins 12 valve I don't think it's the return line. Removed all the injectors today reinstalled them. Looks like that fixed the problem for 3 of them. I can see bubbles around the retaining nut. I torqued them back to 44. I might take it another pound or 2. Hopefully that will fix that issue. Attached Images

01-17-2019, 08:32 PM	#24
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,139	Re: C20/cummins 12 valve The problem isn't the retaining nut torque. Your nozzles are leaking past the threads where the nozzle nut screws on to the body. I'm guessing by the looks of the paint on the body these are used or original to the engine? __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

01-19-2019, 11:36 AM	#25
Vintage Windmills Vintage 4x4s Join Date: Sep 2010 Location: Prior Lake, MN Posts: 4,305	Re: C20/cummins 12 valve Cool project and nice longhorn! Are you looking for a suburban in general or one to put the cummins in instead of the longhorn? Are you going to check your head for cracks? Some of the non IC 6BT's have them. __________________ 67 GMC K1500 Custom- 305V6 SM420, PTO, Ram Assist, yellow (the outcast) (project period correct upgrades) 67 GMC C2500 351V6 TH400, AC, PS, PB (can't decide what to do with. Update, decided to keep and will restore ) 86 CHV K30 502 th400, apple red NEW 71 CHV K20 350 SM465, ochre (saved work truck) 71 CHV K20 292 SM465, white, tach, PTO, (future project) 72 CHV K20 350 350th, medium blue (project stocker) 01 CHV K2500hd crew, indigo blue ^3 dont run and the others don't see winter either '86 K30 Cummins "Fireside" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=649649 '71 K20 "get driveable" thread: http://67-72chevytrucks.com/vboard/s...d.php?t=590642 '72 K20 Build Thread: http://67-72chevytrucks.com/vboard/s...=493477&page=6

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