OMC 3.8 Chevy 229 block cracked

[Howard Sterndrive]

The only option for aftermarket is OSCO. All others will interfere with the Selectrim trim ram/engine mounts.

I fixed up some cracked 3.8 manifolds years ago. Mine were mainly just pushed out on the lower rear curved parts, and then split near the drain fitting. I veed the cracks out with a die grinder, then drilled the ends of the cracks to relieve stress. Then I used a mix of JB Weld and fiberglass strands to fill. They worked great for 3 or 4 seasons. Then I found some NOS manifolds and foolishly tossed the repaired ones.

 

[omc_parted]

Working with OSCO now........they are cross referencing my OMC p/ns to theirs. Not willing to blow my valves on a repair Looks like the starting price is around 225$/manifold. Can prolly get cheaper once I got the right p/ns. Crossing my fingers

 

[HT32BSX115]

Looks like the starting price is around 225$/manifold.

Consider yourself lucky that you can find good replacements!!

If you had an OMC 460, you'd be looking at new "old-stock" manifolds for about $1500 each! and stainless after market manifolds at around $3000 for a pair or an HGE adpater+ 454 manifold combination for $1400.

Most of us are glad you're not going to risk your engine with a welded/glued temp fix!

 

[omc_parted]

UPDATE: Osco cannot guarantee that their manifolds will work. Apparently the guys that used to know these parts well all left. They are not sure these will clear the trim jacks OR the valve covers. I got a lead at the old junkyard up at the lake who should have a pair, not sure what shape they are in.
In the meantime, I got some high temp stuff (2400 degree F) that could serve as a very temporary fix for these little cracks.Will try it out tomorrow. Its called QuikSteel. Best hope I got for now. Dammit

 

[Howard Sterndrive]

The outside of those manifolds won't exceed 220F - marinetex or JB +fg fine.

Should be lots of old threads on iboats showing OSCO conversions on 3.8's, but they're a center riser setup, so the whole setup will be around $1300 new once you buy the risers and hose/adapters etc.

 

[omc_parted]

Ahhhhhhhhhhh..........I see the trim jacks in the picture My OSCO p/n is CSCR618. Wish i could tell what these guys are. Also, saw new mannys going for 180$/unit, with risers around 100$/unit. Mebbe I'll ride that OSCO train after all Also, I got replacemnt hoses at home depot for 5$/hose. Cheap is my middle name

By the way, that is one clean setup there. Very pretty

 

[boatermarquis]

Use that marine stuff,its better than jb weld,don't remember the name,but it works,and lasts.

 

[Howard Sterndrive]

one here for $150 http://www.ebay.com/itm/Osco-CSCR618-GM-V6-3-8L-Exhaust-Manifold-/171382765932

 

[omc_parted]

Found that one first on ebay. He only has the one. All other sites sell from 180$ and up. Discontinued after OSCO got sold? Either way, gonna use the old ones just to check the 1st run and THEN get either 1) the ones from my junk boat parts dealer (lanier marine liquidators) or b" OSCOs. Not gonna rebuild this sucker twice

By the way, Happy Turkey day everyone

 

[omc_parted]

Update: Found about a dozen manifolds at the junkyard, pulled them off of old 3.8s. EVERY one of them had miscellaneous cracks, some in the same place as mine, some had cracks at the exhaust ports.Total fail. JB weld (high temp) along with the high temp steel epoxy stopped the leaks. For now. Ended up with ANOTHER leak in the old water pump. Not from the seep holes either. New pump (40$ including shipping) from Amazon here by Dec 11.Got the motor all wired up for REAL first run. Ya'll will laugh when I finally post the pics of my setup.

If anyone needs any 3.8 parts, I got a motherload of stuff at the junkyard. Let me know and we can prolly scrounge it up for ya

 

[omc_parted]

Latest and greatest update: All water leaks solved, new water pump works fine. Last issue is distributor. I read somewhere on this forum that the semi-even firing on this engine makes the dizzy setting difficult. I think I finally got it right, no more backfiring out the carb, but couldn't find the mercruiser manual (#7) that steps u thru the process. Anyone got a working link for the directions? I actually saw exhaust blast out the bellows for the first time, but still doesn't want to start and run. Thanks again for all the assistance

Found the manual on ebay total includes shipping 8$. Wish me luck

 

[Bondo]

Latest and greatest update: All water leaks solved, new water pump works fine. Last issue is distributor. I read somewhere on this forum that the semi-even firing on this engine makes the dizzy setting difficult. I think I finally got it right, no more backfiring out the carb, but couldn't find the mercruiser manual (#7) that steps u thru the process. Anyone got a working link for the directions? I actually saw exhaust blast out the bellows for the first time, but still doesn't want to start and run. Thanks again for all the assistance

Found the manual on ebay total includes shipping 8$. Wish me luck

Ayuh,.... I just found it right here in Don'S Aduts Only section links,....

 

[omc_parted]

omg I am an idiot. I saw that in the sticky before and didnt figure out that u can scroll thru the rest of the manuals via the little horizontal slide bar on the site. Thanks, Bondo

 

[bruceb58]

I use those online manuals when I am helping someone with their boat. So much nicer having your own paper manuals though for your own boat.

For OMC, they don't have the factory OEM manuals as far as I can tell...just aftermarket.

 

[omc_parted]

Got the manual on cd....not too shabby. Dumb question follows:

I'm not starting, got fuel, ignition, distributor correctly installed, no backfire thru the carb, but i noticed a lot of fuel on plugs 3, 5 and 6. I checked spark on all 6, its there. Maybe not enough spark? I never changed anything on the carb itself, worked fine before i trashed the thing. Got new gas, high octane too. Noticed that when i start it after letting it sit for awhile, i can see the exhaust shoot out of the intermediate drive. Then it stops shooting water, exhaust all together. Flooding?

 

[Howard Sterndrive]

a compression test will verify cam timing and valve adjustment ok.

 

[omc_parted]

Compression test yields all zeros, all cylinders. Not believable. Valves open and close during turnover. Checked all plug wires. Lo and behold, one was completely open, two others read way high on resistance. New plug wires on the way from Amazon

 

[stackz]

sounds like you might have the cam out of phase.

why not pull one cylinder to TDC and check to see if a valve is still open on that cylinder, then check on the other ones.

 

[Bondo]

sounds like you might have the cam out of phase.

why not pull one cylinder to TDC and check to see if a valve is still open on that cylinder, then check on the other ones.

Ayuh,.... I'd sooner think when the valves were adjusted, they were wound down Way to tight,...

 

[omc_parted]

I got number one cylinder right (after all the research). Watched as the valves opened and closed coming around to number 6 firing position and then no movement on compression for number 1. Guess I'll pull valve covers and watch as I slow walk the crank. Could be off but I did follow the instructions in the Clymer manual. adjusted intake 1,2,3 in TDC, exhaust for 1,5,6 and then rotate again to timing mark for intake 4,5,6, exhaust 2,3,4. Doesnt hurt to recheck Thanks guys