1988 OMC 4.3 2V - Leaking Manifolds

[theundercut]

EDIT: Sorry Wrong Location, please delete. I will post in the appropriate forum!

I was given a 1988 Four Winns 4.3L OMC 2V which had been sitting for a couple seasons. The owner said they winterized it thoroughly but when I got it started up water was leaking out of cracks on the manifolds both port and starboard. It appears to be exterior cracks but I wanted to see if there is a way to make sure water is not going through the walls. I was thinking a type of leak down test. Upon searching the topic it appears these one piece "batwing" style manifolds are an issue. Currently there is no water in the oil although I only ran it a few minutes upon discovering the leaks. The engine ran and sounds great. Upon searching for the new manifolds it appears the after markets come in 2 varieties, GLM and Barr. Barr having the more positive reviews. My only issue is that when I look up Barr the manifolds all state for OMC 4.3 1989 and later. I cant seem to find the correct ones for my engine. Can anyone that has done this point me in the right direction? I am thinking I should just bite the bullet and replace them.

 

[theundercut]

I was given a 1988 Four Winns 4.3L OMC 2V which had been sitting for a couple seasons. The owner said they winterized it thoroughly but when I got it started up water was leaking out of cracks on the manifolds both port and starboard. It appears to be exterior cracks but I wanted to see if there is a way to make sure water is not going through the walls. I was thinking a type of leak down test. Upon searching the topic it appears these one piece "batwing" style manifolds are an issue. Currently there is no water in the oil although I only ran it a few minutes upon discovering the leaks. The engine ran and sounds great. Upon searching for the new manifolds it appears the after markets come in 2 varieties, GLM and Barr. Barr having the more positive reviews. My only issue is that when I look up Barr the manifolds all state for OMC 4.3 1989 and later. I cant seem to find the correct ones for my engine. Can anyone that has done this point me in the right direction? I am thinking I should just bite the bullet and replace them

 

[Scott Danforth]

You will need to get rid of the batwings.

@Lou C did it a while ago and had a good write up

 

[Lou C]

Before I invested $$$ I’d make sure that the block isn’t cracked. Look way down in the area above the oil pan (in front of the starter on the starboard side & in front of the oil dipstick tube on the port side) for rust stains….if it’s OK… those Batwings were used from 1985-1990, after that OMC switched to the 2 piece design & Volvo bought out the OMC sterndrive line & used the exact same design. So those Barr manifolds or the GLM kit will fit all OMC or Volvo 4.3s. In fact Volvo used the same exact design till they had to switch to cat converter exhaust. So despite the error in the catalog those Barr manifolds will fit your engine. You may have to remove the studs that OMC used for the Batwings & use the bolts that come with the Barr units. To make it work with the Barr parts you have to buy (new or used) the Volvo Penta 90* aluminum down pipes that adapt the 4” elbow exit to the 3.5” OMC Y pipe & the hoses & clamps that go with it. That’s the way I did it because at the time the local parts shops here advised that Barr was better quality than GLM (who sells the whole kit). Not sure if GLM quality improved since then. Mine fit perfect no leaks. Installed in 2017. Do a search on my user name I did post the V/P part numbers that I used at one point. If you buy new it is a bit pricey.

 

[theundercut]

Before I invested $$$ I’d make sure that the block isn’t cracked.

I had a mechanic over to take a look at it, there are no signs of a cracked block that we can find. It ran for a bit before noticing cracks in the tops of the manifolds and water spitting out. I'm not sure if this is a result of freezing, it seems like an odd spot to crack from freezing, up high on the top of th manifold walls. No excessive smoke from the engine, no drip stains identified on the pan, ran like a top, oil looked like it was straight out of the bottle, took the cap off and looked at the top and no milky residue signs. I know the previous owner very well and he informed me it was always winterized, he is a competent person so I lean towards it being done correctly. All that being said I know its a gamble but I'm going to go for it.

To make it work with the Barr parts you have to buy (new or used) the Volvo Penta 90* aluminum down pipes that adapt the 4” elbow exit to the 3.5” OMC Y pipe & the hoses & clamps that go with it. That’s the way I did it because at the time the local parts shops here advised that Barr was better quality than GLM (who sells the whole kit). Not sure if GLM quality improved since then. Mine fit perfect no leaks. Installed in 2017. Do a search on my user name I did post the V/P part numbers that I used at one point. If you buy new it is a bit pricey.

I found your post. I was planning on purchasing this kit. It looks like I am going to need a couple more pieces.

Does this look correct for the 90's, hoses and clamps?



Thank you again for your help!

 

[Lou C]

Yep that’s what you need. When you install the gaskets between the manifold & elbow follow the manufacturer’s instructions as to whether you need sealer or not & torque specs. I re-torqued mine after running it for a while….

 

[Lou C]

Yep that’s what you need. When you install the gaskets between the manifold & elbow follow the manufacturer’s instructions as to whether you need sealer or not & torque specs. Volvo actually revised their gaskets a few times. I used the Barr gaskets with no problems.

 

[theundercut]

Yep that’s what you need. When you install the gaskets between the manifold & elbow follow the manufacturer’s instructions as to whether you need sealer or not & torque specs. Volvo actually revised their gaskets a few times. I used the Barr gaskets with no problems.

Ok, thanks! What about between the manifold and the block? I can’t seem to find that info, you wouldn’t happen to know?

 

[Lou C]

Those go on dry no sealer...

 

[Lou C]

Here's mine when I was trial fitting all the parts.


an easy way to install the manifolds is to take a bolt from the kit and go to the hardware store and buy 2 identical pitch but longer bolts. Cut the heads off and cut a slot in the stub. Thread one the first and last holes in the cyl head for the manifolds. Slide on the gasket, then slide on the manifold. Install the rest of the bolts and use a screwdriver in the slot you cut in the stub to remove them. Install the last 2 bolts. Easier than trying to hold up the heavy manifold and keep everything lined up.

 

[theundercut]

Here's mine when I was trial fitting all the parts.
View attachment 384964

an easy way to install the manifolds is to take a bolt from the kit and go to the hardware store and buy 2 identical pitch but longer bolts. Cut the heads off and cut a slot in the stub. Thread one the first and last holes in the cyl head for the manifolds. Slide on the gasket, then slide on the manifold. Install the rest of the bolts.

Good idea, I need to find the torque specs. I can’t seem to find a manual.

EDIT: Scratch that some more searching I found one online. 86-98 OMC Sterndrive Manual

EDIT 2: 30 ft.lb for the intake manifold on this engine, 18-22 for the exhaust for anyone that happens to come across this in a search.

 

[theundercut]

Easier than trying to hold up the heavy manifold and keep everything lined up.
View attachment 384965

Ok, I’m moving along. Since the manifold was off I decided to pop the valve cover and take a look.


Looking pretty good no signs of water getting in, feeling confident.

Getting the studs out was a PIA. Generous amounts of pb blaster and heat did the job.

Since the covers were off I decided to add 5hp .



You mentioned looking up the gasket to see if I needed sealant. It’s Armstrong mp-15 and I can’t seem to find any literature on it. Any thoughts?

 

[Lou C]

If they are paper gaskets I would use sealer if they are composite gaskets with the silver backing they may not need it. I suggest removing the paint from the sealing surfaces.
You bought them from Marine Engine Parts AKA Lighthouse Marine? They are local to me (Riverhead Long Island NY). Give them a call & ask…

 

[Scott Danforth]

Good idea, I need to find the torque specs. I can’t seem to find a manual

Only legal place to get factory manual

Original outboard product and service manuals for Johnson, Evinrude, Gale, and OMC

Ken Cook Co. sells Original Product Literature Supporting 1996 and Older Outboard Marine Corporation Products, limited supply of original printings of Johnson, Evinrude, Gale, and OMC manuals are still available. On older literature, we may provide a machine copy reproduced from a master file...

outboardbooks.com

 

[theundercut]

If they are paper gaskets I would use sealer if they are composite gaskets with the silver backing they may not need it. I suggest removing the paint from the sealing surfaces.
You bought them from Marine Engine Parts AKA Lighthouse Marine? They are local to me (Riverhead Long Island NY). Give them a call & ask…

Did you have any issues with the hoses reaching the manifold from the thermostat housing? They are coming up a bit short on mine.

 

[Lou C]

I don't think so, I know I replaced them at some point, might have made the replacements a bit longer than the originals. IIRC they are just 3/4" hose, you can use automotive heater hose, the water doesn't get very hot and not under much pressure either.