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Old 03-07-2011, 08:18 PM   #1 (permalink)
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6.2 oil cooler line leak repair

Hi all first post.

This is a quick DIY guide to repair the 6.2s oil cooler lines.

My '89 K2500 had been seeping oil where aluminum crimps meet the rubber oil lines for years and built up about 1/2 inch of oil. Please note that I did not replace the lines entirely but replaced the rubber hose section. Total installation time was approximately 2 hours from removal to finish.

My plan of attack was simple: the fittings were not leaking or had rusted clips (bock fittings) and I did not want to disturb them. For a quality budget repair I cut out the old rubber lines and replaced them with compression fittings and hydraulic hose. I retained as much old aluminum line as possible. No more leaks.


Parts List:

1. 4x 1/2" ID brass compression fittings. Two for each line to and from the oil cooler. These can be found at Home Depot or Lowes aprox $3.50 each

2. 2x 1/2" ID hydraulic hose. 48" long worked absolutely perfect. Found at Tractor Supply Company for $17 each. Verify that your compression fittings thread onto the hydraulic hose ends.

Total Cost: ~$50


Tools Required: Only basic hand tools such as a socket set and pipe cutter/hacksaw blade.



1. Locate the oil cooler lines. Determine if the fittings leading into the block/oil cooler are leaking. If so I recommend replacing the oil cooler system with Lubrication Specialist.comís stainless steel line kit. Click here for their website.
2. If your fittings are not leaking check for oil seepage underneath the aluminum crimps It may be very obvious, as oil may have built up under the lines. Wipe clean the crimps thoroughly, check for leaks, run the truck a few miles and check again. I found obvious signs of fresh oil seepage under the crimps (both near the firewall and under the oil cooler).
3. Drain your oil.
4. Remove the skid plate (if applicable) beneath the grill to gain access to the aluminum lines leading to and from the oil cooler.
5. Disconnect the steering column as it blocks easy access to the lines. One bolt and it pulls down and off with only a bit of effort.
6. Cut the aluminum lines as close to the crimp as possible. I started it with a pipe cutter but finished with half of a hacksaw blade. Remove burrs and carefully wipe out any aluminum bits.
7. My compression fittings came with a flared brass sleeve aprox 5/8Ē long. This sleeve slides into the inside of the aluminum line first. The brass nut slides on next. If you have burrs the brass nut may have some resistance.
8. Wrap fuel rated Teflon tape on the fittings. Pipe compound or regular Teflon tape will work as well.
9. Torque the remaining ends of the compression fittings onto the hydraulic hose.
10. Route the hydraulic hose in the same fashion as the old hose.
11. Wrench tighten connections.

1989 K2500 Silverado 6.2L 4 speed 118k miles
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Old 03-07-2011, 08:24 PM   #2 (permalink)
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Oil cooler repair pics

Attached Images
File Type: jpg lines to block.jpg (87.9 KB, 1203 views)
File Type: jpg cooler lines.jpg (85.1 KB, 2106 views)
File Type: jpg Fin.jpg (83.3 KB, 1373 views)
1989 K2500 Silverado 6.2L 4 speed 118k miles
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Old 03-07-2011, 09:39 PM   #3 (permalink)
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Heck of a first two posts

Nice job

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Last edited by Joeairforce; 03-07-2011 at 09:40 PM.
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Old 03-08-2011, 02:42 PM   #4 (permalink)
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Nice job
1982 GMC C2500 HIGH SIERRA 6.2 J n/a THM400 trans, 265/70/r16 tires, 4.10 gears, AND A AGRESSIVE DRIVER, AIR BRAKES COMING SOON
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