I have a 89 Blazer which has developed over night an oil or tranny leak that only happens under pressure when the engine is running

It is coming from a pair of 1/8th inch double metal lines that loop down under the engine by the transfer case / flywheel and then disappear up again. Does anybody know what exactly these lines are, where they connect and if it is a DIY for a handy person with only normal tools.

Below are 2 pictures I took. Any help or suggestions would be greatly appreciated.

 

Looks like trans cooler lines. They go from the trans to the radiator. You should be able to R&R those yourself with wrenches. You may want to invest in a set of "line wrenches" for that job. Line wrenches are cupped more than standard wrenches for grabbin flange nuts better. Regular wrenches can round em off easily.

They prolly dont come pre bent, so you want to remove the old ones and measure them so you can get appropriate legnth of pre flanged tubing. Then careful bending the new ones to match so you dont kink em.

 

I believe you may have luck finding pre-bent lines at LMCtruck. I'm not sure, but I know they had the remote oil-filter lines in stock when I needed to replace them. Leads to an easier day of repair work.

Otherwise, agree with the above post. Get yourself a good set of line wrenches (also sometimes called flare wrenches) and you can easily buy a cheap bender and some new line if you can't find a pre-bent set.

 

1/8" would be the smallest trans cooler lines I've ever seen. Those look like brake lines. Take a white paper towel or Kleenex & dab the fluid... what color is it?
You don't want to rub or wipe it because of the rust that will discolor the results & you may bend something & make a bigger hole.
Get a pair of safety glasses & someone to start the engine. Have them press on the brakes & see if more fluid comes out.
Safety glasses are EXTREMELY important with brake fluid!!! Brake fluid will absorb moisture - think about that in your eyes!

 

I could be wrong, but I was under the impression there is only one brake line to the rear of the truck? It reaches the rear diff and splits to go left/right from there. This is certainly true on my '94 (mine only has one rear line even w/ ABS). I suppose it's possible it was changed at some point....

 

I'm not sure either, but I can't think of any other line that would be made like that in that diameter.
'89 - '94 there could be many differences. Take for instance my '02... I kept reading about the EGR & cleaning it, how much of a PITA they can be. Turns out my late model year '02 didn't have an EGR.

 

True, True.....

 

Of course I can't find my GM Service Manual anywhere. Been busy with work to take much of a look so far. But I can tell it is not a brake line. Fluid is different then brake fluid and it is a constant pressurized leak when the engine is running. No change if I pump the brakes. I'll post back this weekend once I have some time.

 

I would say tranny cooler lines.

 

They are definitely not 1/8" lines and they definitely are the transmission cooler lines. To prove it to yourself, they should run from the passenger side of the transmission up to the passenger side of the radiator.

I would cut out the bad section & use compression fittings to splice in new line. Just measure the OD of the line up near the radiator to get an accurate measurement to make sure you get the right size. Replacing the whole thing is all fine and well, but over kill IMO. There isn't a lot of pressure in trans cooler lines (30psi max IIRC).