1989 Johnson 40hp VRO crack in intake runner

[natestep]

I just bought a boat with this engine on it. I knew of the problem when I bought the boat. I pulled the plugs out of it cause I thought it had thrown a rod. Both of the pistons are moving and there is no knocking and I put my finger over the plug hole and it appears to have plenty of compression. The crack is in the upper intake runner on the right side of the engine. The guy said the engine was running fine and it just died like he had turned the key off. I have fire at both cylinders. The engine will not start. I cant figure out what would have caused the crack in the intake. It is about an inch long and is a real thin crack. The VRO pump was removed several years ago and he was mixing the gas 50:1. Please help

 

[levi_tsk]

Re: 1989 Johnson 40hp VRO crack in intake runner

crack on intake runner like on the intake manifold?
sounds like it got really hot to me that or he got too rowdy with the wrench when he tightened something up?
if its on the block its probably toast otherwise you MAY be able to get it welded up
and if it got too hot id be checking the compression BEFORE i spent another dime on it ... get on ebay and buy a compression tester i got mine for 15 bux shipped its a harbor freight brand but it works fine for what your doing
DO NOT USE THE ADAPTER THAT COMES WITH IT!!!!!!!!!!!!! give it a few pulls (or revolutions) on the starter until the psi stops rising do BOTH cylinders then come back and tell us what you have

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

Ok will do thanks!

 

[levi_tsk]

Re: 1989 Johnson 40hp VRO crack in intake runner

so is it on the intake manifold?

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

so is it on the intake manifold?

Thats what I would call it. Im a certified GM and Mopar mechanic, but far from a marine mechanic. If you look at the right side of the engine, on the rightside and behind the starter, it appears to be an intake runner. The crack is only an inch to an inch and a half from where it bolts to the block.

 

[boobie]

Re: 1989 Johnson 40hp VRO crack in intake runner

Your pics aren't that clear but it looks like something broke loose in the p/h. Maybe a loose rod bolt?

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

Its no good like it is so Im gonna tear into it tomorrow. The engine turns over smoothly and makes no sounds. Like I said the piston is moving so it may have just lost one of the rod bolts. I might can fix it if thats all it is. Hope so. Thanks for the help, the crack is so small that I had to get close so it could be seen. Sorry for the bad pics.

 

[Faztbullet]

Re: 1989 Johnson 40hp VRO crack in intake runner

If its not knocking it likely a piece of piston skirt broke off and got in front of rod "ventilating"front crankcase.

 

[boobie]

Re: 1989 Johnson 40hp VRO crack in intake runner

Tear it down and see what's wrong. If it's easy to fix, blocks can always be welded.

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

Broke piston skirt dont sound good at all Ive never built a boat motor, several car engines but no marine engine. If its something like that I will probably just buy a used powerhead. Im still gonna tear it down tomorrow and let yall know. Thanks for the replies.

 

[Jayrock]

Re: 1989 Johnson 40hp VRO crack in intake runner

Broke piston skirt dont sound good at all Ive never built a boat motor, several car engines but no marine engine. If its something like that I will probably just buy a used powerhead. Im still gonna tear it down tomorrow and let yall know. Thanks for the replies.

Its not any more complicated to rebuild an outboard engine than a car engine, I bet you already have all the tools. Especially a 2 cyl engine. Piece O' Cake

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

Yeah I have tools out the yang. I rebuilt a Suzuki engine in a Tigershark jet ski a couple years ago. It wasnt bad at all other that bend over and working in that hull. I guess we will try it if I have to.

 

[boobie]

Re: 1989 Johnson 40hp VRO crack in intake runner

You won't know what's wrong with it until you get into it. Keep us posted.

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

Tore it down this morning and the rod bearing failed. Shavings everywhere, ruined crank, got into reedbox real hard, bent rodcap bolt, and punched two holes in the block. It looks like a good canidate for a parts powerhead. I tried to take pics of it all but with that dandy camera they didnt turn out. Thanks for all the help guys. I think there was an obvious lubrication issue. Im just gonna get another power head.

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

Just one more question for you guys though. I heard the powerhead swap is fairly easy. From what I can see im gonna hafta drop the lower unit and get to the base bolts from there. Am I correct on this?

 

[boobie]

Re: 1989 Johnson 40hp VRO crack in intake runner

If you already have th p/h off why would you want to drop the l/u unless to service the water pump??

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

I dont have the powerhead off. I just pulled the carbs and reedbox. Im gonna change the water pump too though cause its been setting so long. It appeared that the top carb quit working causing the failure. I looked at the bottom bearing and I could see oil on it.

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

I won the powerhead. I wound up getting it for $374.00 shipped. Its complete from the breather box to the spark plugs including all the electronics. I think it would probably be the best fix.

 

[natestep]

Re: 1989 Johnson 40hp VRO crack in intake runner

Thanks for all the help on this guys. I changed the powerhead out yesterday and it was a piece of cake. I also rebuilt the water pump which was much needed. All three veins were weather cracked almost in two. I took it to the river and it fired right up and ran great. Thanks for all the help on this deal, I couldnt have done it with out ya. The trim cyl. is leaking bad so now I gotta find a repack kit for it and get that leak stopped.

 

[ONERCBOATER]

Re: 1989 Johnson 40hp VRO crack in intake runner

i would humbly suggest running sea foam and a 40:1 oil mix in the "new" powerhead, just for a tank or two for the 40:1 and heavy sea foam at 1st as a treatment, then use it at maint levels. I would also suggest that you put the other powerhead back together with everything inside sprayed with a fogging/preservative oil, and then wrap it up in a nice cardboard box, that way you will have all the parts you need in a nice tidy easy to find package.

congratulations on the running engine.

Sean