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Cracked block, anybody seen this before?[200/85] posted by Rob Hanley on
Thursday, 14 December 2000, at 11:24 p.m.
My '85 245 has been leaking oil from an unknown-to-me source since about 197k. I now know why. I was going crazy trying to find the source of the leak, until I decided to spray down the engine bay. Now I'm starting to wish that I hadn't done that. There appears to be a crack in my block, down by the foundry mark. It isn't very big, maybe a quarter of an inch long and 1/3 of an inch in diameter. It leaks out about half a quart of oil in a week.
Niiiiiiiice. I guess that's what I get for being an obsessive "maintenance-aholic." I'm sure Don Foster is gonna blame this on my use of Fram oil filters. So guys, give it to me straight. How much longer do I have? What are the chances of the "crack" getting bigger? If I keep topping off the oil, how long can I avoid throwing a rod? Should I try something like JB Weld on this??
--Rob
Re: Cracked block, anybody seen this before?[200/85] posted by Don Foster on
Friday, 15 December 2000, at 4:47 a.m.
"...blame this on my use of Fram oil filters..."
No, no. This is just bad luck.
But before you panic, confirm that you really have a porous block (it's possible). Then ask several "old time" mechanics about tricks to seal leaks in cast iron blocks—they ARE possible to fix.
You'd need to clean the cast iron very well, starting with good solvent and then perhaps glass-blasting the local area. Then you might try:
- Peening
- JB Weld (this doesn't make me feel good)
- Solder (getting better)
- Braze (better yet)
- Arc weld with nickel (works very well with cast).
I've brazed and (nickel) arc welded cast iron very successfully. My concern with arc welding is that the casting might be super thin at that point, and an arc might blow right through it.
Though I take a lotta ribbing about soldering everything in sight, it really IS a method worth considering. It requires less heat then brazing, and considerably less than welding. In this case you'd use plumbing solder, and you can probably do it with a propane torch.
I soldered up 20+ rust pinholes in my differential cover, and it has lasted well for years.
Don Foster (near Cape Cod, MA)
--Friday, 15 December 2000, at 9:11 p.m.
I've tried Stainless steel wire and mig welded a block shut. Super clean the weld area and pre heat with a heat gun to the point that it is just too hot to touch. then gently peen the weld and immediate surrounding area after welding to relieve some of the stresses.
--200 series braces done.
Re: Cracked block, anybody seen this before?[200/85] posted by Al on
Saturday, 16 December 2000, at 4:40 p.m.
Cracked block....JB Weld type....If you can get to the damaged area...there are two products I have used on industrial engines very successfully...each is a cold paste applied polymeric type poduct...not cheap but it works when done correctly..look for THORTEX (try www.thortex.com) or BELZONA ( not sure of their web)...cost several hundred dollars for the kit....but well worth it...in any repair (weld, filling, etc.) the crack must be terminated (drill a hole at each end of crack as well as each turn or split off of crack) to prevent "crack creep"..."V" out crack between drilled holes...clean and decrease the repair area with a good decreaser (usually comes with kit) which leaves no residue...the secret here is CLEAN...mix the two part paste, wet out the area with the paste and smear it on.....let cure or help it along with a hair dryer....if you get the kit follow instruction to a "T"...I have done off road vehicle engines as well as large truck engines (diesel and gas) and auto engines...either product is not for use in high heat areas (exhaust flanges, pipes, headers, combustion chambers, etc.) Takes a good days work (and then some) to do the job. Hope this helps...and have a Merry !!
--al