OMC 4.3L Problems

[Len2020]

So here’s the story shorten up I just bought the boat 22ft with the 4.3l guy had it in water a year ago and ran great has service receipts and all kinds of paperwork. He told me it was water ready. I bought the boat took it on the water and was running great. I then smelled something weird and when I shut the boat off to go smell it I herd water boiling almost sounded like inside the motor but wasn’t positive but also didn’t see anything else that caught my eye. I was watching the gauges and I had Over 40 psi oil pressure and also had the temperature going up around 180 but when I shut the motor off and noticed that the temperature kept going off but when driving for about 15-20 minutes it was fine I wasn’t going any higher. When does start Boat found out it wouldn’t turn over got it back home took out starter. starter tested good, motor was seized but still could turn it a tiny bit from a
screw driver on the fly wheel. I then proceeded by taking the spark plugs out and found out that water came out of cylinders 2 and 3 I believe across on each side. My question is I would like to rebuild the motor from top to bottom but I’m not sure where to start or is it better to just rebuild the top end because the motor sounded fine. I also can buy a motor that runs from my car same motor 4.3 L same year 1987 has everything with it and runs for 350$

 

[alldodge]

Howdy
Motor got hot probably because the impeller needed to be changed.

You can change the motor out but want a motor from a truck not a car because different cam. Would also need to change out freeze plugs from steel to brass or stainless. Could use the block and swap the cam.

Might want to look at your motor before going further. It may just need new head gaskets and head work

 

[Scott Danforth]

if you have the original bat-wing manifolds, they may have failed. it is highly recommended you change the batwings

do a cooling system pressure check and a compression test and check your motor out prior to throwing money at it. you may simply need new exhaust or head gasket or something minor.

you need a 4.3 from a truck (and you are only going to use the long block). you will need to change to marine head gaskets and brass core plugs. if you pull one from a car, you need to change the cam and a few other things.

 

[Lou C]

You might have a few different problems going on. One the impeller may need to be replaced and if you have a Cobra drive the impeller is very easy to change (under a cover at the rear of the upper gear housing). However failure of the exhaust system can cause both of the problems you had. If it’s an 87 then it has the one piece bat wings that are probably long past replacement time and are NLA. You can upgrade to the later 2 piece system using good aftermarket parts (Barr Marine) and Volvo Penta exhaust pipes and hoses.
before pulling the engine get the water out of it after draining it and the exhaust and see if it will crank over with the starter (ignition disabled). If so and you don’t hear clunking noises when it cranks (sign of a bent rod from a hydrolock), it might be salvageable.

Id take off the manifolds and prop em up level. Carefully fill with acetone (flammable) and see if you get staining in the ports that line up with the exhaust ports in the cyl head; if so they are junk. Also make sure the exhaust flappers are in place at the top of the Y pipe, if not they can drop down and clog the exhaust; this can cause overheating and other problems.

If you need to change the exhaust to the 2 piece do a search on my user name I posted up pics and part numbers...

 

[Lou C]

here's some pix....

 

[Len2020]

The previous owner replaced the water pump in the cobra drive multiple times he was original owner and he would replace it every three years but I did pull apart just to see if it was good and look brand new but I found little tiny pieces in the left side port from an old one. I flushed it out but I’m going to try hooking the ears up and see if water comes out the spark plugs if it does I got a problem with the head or exhaust I assume hopefully it’s something easy I would like to rebuild the motor instead like I said I can move the motor with a screwdriver where the starter goes but I cannot move it from the alternator or turn it with a strap wrench but I can inch it on the fly wheel I really do hope the block is still good and it is salvageable. Will keep everybody informed what is going on new west marine engines feel very comfortable with cars

 

[Len2020]

I turn the water on and let it run for like five minutes still have not seen anything come out of the spark plug holes I guess I’m going to pull the engine out this week possibly I’ll take photos of the engine and post them before

 

[Len2020]

The starter won't turn the engine as it is frozen and also there is no water in the oil.

 

[Len2020]

https://youtu.be/5ImT92pB2Dk

 

[alldodge]

The motor has had lots of water where it shouldn't be

 

[Lou C]

Yep and the "4.3 Litre" decals on the manifolds tells me they were ORIGINAL because I ran 2 sets of OMC replacements and they didn't come with those decals but my original ones did. Got the boat in 2002, changed em the first time in 2005, then again in 2011 then converted to the 2 piece late OMC/Volvo Penta system in 2017. None of my bat wings ever leaked but then I didn't keep them on too long either.

 

[Lou C]

I turn the water on and let it run for like five minutes still have not seen anything come out of the spark plug holes I guess I’m going to pull the engine out this week possibly I’ll take photos of the engine and post them before

PS just turning the water on with the engine not running will not tell you anything, the engine has to be running and water pumping through the system. Water doesn't even get past the impeller blades in the upper gear housing with the engine OFF. So that poor engine died from either bad manifolds (seems likely judging by the pix) or a blown HG (possible that flapper looked a bit melted in the vid, but not totally melted off).

 

[Len2020]

Do you think I can redo the top end and save the engine or do you think it’s no good?

 

[Lou C]

well you can try. pull the heads, and look and see how rusted the cyls are. If very rusted/pitted forget it, if not, fill the cyls with PB blaster or Kroil and let it sit for a week or so. Then see if you can get it to turn. Very carefully...lube the cyls with fogging oil for that part..
When my HGs blew, I had salt water in 2 cyls for a few days but I caught it fast. Blew out the water, drained the motor and manifolds, tested the manifolds (they were good so I knew it was a bigger problem). Tested for combustion gases getting in the cooling water and found it. Pickeled the engine with fogging oil liberally and took it apart the following spring. Motor turned over VERY easily. Took off the heads and brought to the machine shop. Heads had cracks from a previous overheat, but block still looked good and flat & level to less than .003". Bolted on a set of reman heads, Felpro gaskets with ARP head bolts. Back in business...but I got the water out fast....