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07-07-2014, 11:24 AM | #1 |
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Re: 89 GMC Cummins conversion
Yesterday I drove it on a 220 mile trip and after about 70 miles noticed that the transmission temperature was creeping up above 200 and finally settled in at 215. So I bypassed the thermostat switch on the trans cooler, added nearly two quarts of ATF and I am pretty sure that the ATF is leaking into the transfer case because there are no oil leaks. On the way home it stayed at about 185 degrees.
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07-07-2014, 08:13 PM | #2 |
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Re: 89 GMC Cummins conversion
Uh oh.. I'm not real good with tansmission or transfercases.. but that can't be good?
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07-07-2014, 08:19 PM | #3 |
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Re: 89 GMC Cummins conversion
That's a bummer. I didn't know the transmission had a thermostat... Guess I had better get educated.
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07-07-2014, 08:59 PM | #4 | |
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Re: 89 GMC Cummins conversion
Quote:
The aftermarket transmission cooler mounted up front has a thermostat that turns the cooling fan on and off, not the transmission.
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07-07-2014, 09:22 PM | #5 |
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Re: 89 GMC Cummins conversion
I found the installation instructions for the B&M trans cooler and the instructions show that the fan is suppose to come on at 176 degrees F (+ or - 5.4 F) and turn off at 140 degrees F (+ or - 5.4 F). I don't think that this is accurate but the next time I take it out I will take my infrared thermometer and check.
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07-08-2014, 01:31 AM | #6 |
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Re: 89 GMC Cummins conversion
Oh that makes sense. I was thinking a thermostat like restricting flow...
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07-08-2014, 07:21 AM | #7 |
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Re: 89 GMC Cummins conversion
That sucks. at least the input shaft seals on the t-case are pretty easy to do. the de-bug process can be a patience tester for sure.
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07-08-2014, 08:13 PM | #8 |
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Re: 89 GMC Cummins conversion
hopefully you will be doing some shake down runs soon. That oil pan is killer!
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09-13-2014, 10:24 PM | #9 |
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Re: 89 GMC Cummins conversion
Not much to report. I have just been occasionally driving the truck around town and to work, which is just one mile away, to keep the batteries charged . I will probably be dropping the transfer case and resealing it after the kid is done with football, basketball jamboree, and the hunting season is over. I sold his 1978 CCLB K35 the other day so I will definitely be giving him this truck. He will barely be 14 this December so I am not planning on doing too much more to it until he is closer to getting his permit. Thanks for following along.
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1987 GMC R2500 SC 454 T400 1988 Chevy R30 CC DRW 12 valve Cummins NV4500 GearVendors Last edited by COS399; 09-13-2014 at 10:31 PM. |
09-16-2014, 03:54 PM | #10 |
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Re: 89 GMC Cummins conversion
I have to say that is a bad azz first truck. I hope I can do the same for my kids when the time comes. It's good to hear it's starting alright now too.
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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. |
09-18-2014, 08:12 PM | #11 |
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Re: 89 GMC Cummins conversion
Thanks Ryan. I'm sure you will have something nice for them. I only have one kid so getting him a vehicle is easier on the wallet. Yes, the truck has been starting right up and I sure am glad I found the problem. We need some updates on your project vehicles.
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10-25-2014, 01:51 AM | #12 |
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Re: 89 GMC Cummins conversion
Hoping to get a chance to work on transfer case seal this weekend to keep the transmission fluid from going into the transfer case.
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11-30-2014, 01:57 AM | #13 |
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Re: 89 GMC Cummins conversion
I still haven't changed my leaking seal and now the heater core has sprung a leak. I have been driving it a lot and I have to say that it does really well in the snow and on the icy roads. However, the mileage hasn't been that impressive.
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11-30-2014, 02:20 AM | #14 |
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Re: 89 GMC Cummins conversion
How good (bad) is the mileage? Glad you are getting some miles on her.
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11-30-2014, 02:21 PM | #15 |
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Re: 89 GMC Cummins conversion
That could be a lot worse! Winter just kills mileage. My tacoma gets down to just over 10 mpg sometimes if I'm abusing the auto start and it's really cold out. You're driving twice as much truck.
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-Marcus 1991 V3500 L29 454 4L80E NP205 D60/14 Bolt 4.56's 1984 K30 292 TH400 NP205 D60/14 Bolt 4.56's flat bed 7'6" Meyer Plow 2022 Silverado 3500 L8T Project Daily Driver Project Heavy Hauler Project Plow Truck |
12-01-2014, 12:25 AM | #16 |
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Re: 89 GMC Cummins conversion
i picked up a heater core yesterday and found some time to get it installed today. Now if I could only find the time to fix the seal. Maybe when Ryan is doing his northern tour he could swing by and fix it.
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12-01-2014, 04:41 PM | #17 |
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Re: 89 GMC Cummins conversion
Don't get too excited. I doubt that trip will be happening anytime soon.
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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. |
01-17-2015, 08:12 PM | #18 |
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Re: 89 GMC Cummins conversion
Any updates i am curious how everything is holding up ? How about the mpg any better ?
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01-18-2015, 02:04 PM | #19 |
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Re: 89 GMC Cummins conversion
72MARIO - Thanks for asking but I haven't had any time to work on it. It will more than likely be a few months before I will get around to it.
I just got done watching the first episode of POWERNATION: Truck Tech involving the installation of a LBZ Duramax and Allison combo in a 1987 C10 short bed.
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01-26-2015, 02:06 AM | #20 |
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Re: 89 GMC Cummins conversion
I know it's not a Chevy and it's not like I have a lot of spare time, but the price was right! That is probably how most of our projects get started. I may one day put it in the "Alternate Tinkering" section.
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04-21-2016, 06:08 PM | #21 |
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Re: 89 GMC Cummins conversion
So today I took the red truck for a little drive and put about 140 miles on her. I checked the mileage and it was 12.5 mpg, but that includes a lot of idling and short trips while tweaking the transmission tune. On my trip today most of the driving was at 75-80 mph. I'm sure the mileage will go up some after I fix the problem with the 3rd to 4th gear shift. I have to say that I got a lot of thumbs up from drivers in the two little towns that I went through.
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01-26-2015, 11:49 AM | #22 |
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Re: 89 GMC Cummins conversion
That is in really nice shape. What are the plans for it?
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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. |
01-26-2015, 01:41 PM | #23 |
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Re: 89 GMC Cummins conversion
I dont recognize the brand, what is it?
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01-26-2015, 08:37 PM | #24 |
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Re: 89 GMC Cummins conversion
Don't really have any plans at the time. I like it the way it is right now.
It is an International. My brother saw the picture and immediately thought of a 6bt conversion.
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01-26-2015, 09:43 PM | #25 |
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Re: 89 GMC Cummins conversion
That would have been my guess, what year? Does it still run?
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