Cat 3116 Expansion Tank Leaks

[EKM]

I just changed my antifreeze to the CAT ELC and now see that both expansion tanks leak from the vertical welds (both leak from the port side) on the bolting brackets. Nothing major but a nice red puddle after each run. Clean it up and see nothing until after a run, so it was leaking only under pressure...tighten all the clamps, but still leaking. Upon closer inspection, found the expansion tank weld leaking (the port engine would was getting worse and would drip even when cool).

Anyway...heads up to look for these types of leaks. Tanks are off now at a truck radiator repair shop for re-welding/brazing over all of the mounts.

 

[Chris1960]

I had exactly the same on my 1996 3126's. After changing to CAT ELC I had a small leak that took me ages to find. (Apparently that stuff is super slippy and finds even the tiniest hole) Eventually tracked it down to under a small rust bubble on the expansion tank mounting points

 

[EKM]

yes...thought I was going nuts. Clamps tight, ELC under the heat exchanger...retighten clamps. I 'm assuming your fixed it rather than replaced the expansion tank. Was it welded or brazed? Mine is off at the radiator shop now...just waiting to here back.

 

[jamesv]

I had the same thing happen to both my engines. I had the tanks and mtg brkts replaced with new and improved versions from CAT. They are built much better and I think they have rubber mounts. No problems since but it was about $700.00ea engine.

 

[osd9]

.....

 

[EKM]

Ouch....can you take a picture of the new mounts? Maybe I can make something up...need some sort of isolator/grommet (studs both ends w rubber in the middle) that would not add too much height.

Dom....that is the location. port side on both engines with 5/16 bolts holding down expansion tank.

 

[Chris1960]

Yep thats the place, just where the mounting bracket meets the tank, there was a rust bubble that had never caused a problem b4 and thats where it leaked out of.
Took ages to find it too
Had mine welded and then etch primed, good coat of paint on it now

 

[jamesv]

I will see if I can take a picture this coming weekend. From what I remember the new mounts are like a rubber grommet with a washer on each side. The tank itself was also "beefed" up. Have you heard back from the radiator shop as to whether they can repair?

 

[The Bill Collector]

I had that mystery leak on my port tank and never found exactly where it was coming from..... So the tank came off, away to the radiator shop, re-welded, pressure tested, primed, painted and back onto the engine.... Not a drop since !

 

[tobnpr]

If you do a search on Boatdiesel, you'll find a lot of posts about ELC causing leaks in the cooling system on "older" CAT engines. My mechanics as well told me to stay away from it...

I do not need freeze protection, so I run Nalcool and water. Otherwise, the "green stuff" and water. From what I've read on these posts, after getting rid of the ELC the leaks stopped. May not be related to your problem, but the problems with the ELC are well documented.

 

[EKM]

The truck radiator place suggested I add rubber isolation...so 8 rubber grommets and elastic stop nuts should help out.

 

[EKM]

Tanks repaired for $80 each...
Found bolt in isolators (1/4" stud at both ends with rubber in the middle) but only rated for 150F which sounds too low. Next approach is to find two rubber pads and sleeve for each bolt location and clamp it down that way (rubber puck, mounting bracket from radiator drill out to accept sleeve, rubber puck and thru bolt).

 

[osd9]

Ed...did you use a radiator shop local at LBI or back home. Pics...we need pics!!!

 

[EKM]

So a little moor research...neoprene is good for 180F. Ordered from McMaster Carr the following. First choice is Sandwich mount if it fits...this will raise tank 5/8". Second solution is the Neoprene rubber washer (using a 3/8" brass insert x 1/2" long x 4x1/8" thick washers....this will raise the tank 1/4 inch and require drilling out the tank mounts to 3/8 in and replacing bolts will long ones.

Install is Friday and pics to follow...so demanding. This is a cheap solution to prevent the tank cracking issue....as long as nothing breaks free 100 miles off shore.

1
Pack 90133A420 Neoprene Rubber Washer 3/8" Screw Size, 13/16" OD, .125" Thick, Packs of 50 $7.43 $7.43 today

8
Each 9213K57 Neoprene Vibration Damping Sandwich Mount Cylindrical Male/Male, 1/4"-20, 5/8" H, 5/8" W (Same as 9376K57) $1.45 $11.60

 

[EKM]

So I used the neoprene washers and spacers. I still have the neoprene isolators. The isolators would have been a much easier install. Although the tank had a 3/8" hole already, so did the bottom mount which required and 1/4 SS washer drilled out to 5/16". Using a 5/16 washer was too large for the spacer. Anyway...alignment was a little difficult for the stack but was much easier to do from sitting behind the engines.

Tank was repaired by Midland Radiator (a truck radiator repair shop in Garfield NJ).

Hopefully good for ever.....now on to the fuel leak. This boating stuff is hard work.