OMC 5.8L cracked hose/water leak

[jmarine225]

Hello, I am new to this board and to boats in general. I have a 1993 Four Winns Vista and just had it serviced where i had a new upper drive installed as the old one was chewed up. After replacing it the mechanic said the engine seemed to be running a little hot so he flushed the engine and found old rubber impeller parts. He said it was still running warm after flushing it so he replaced the thermostat which he said was old and appeared to not be functioning. He said it was running fine around then. I put it in the lake, ran it and the temperature gauge was above 150 getting to about 190-200 at most. This was after running for about 30 minutes. All of a sudden we heard a water leak and steam coming from the engine hatch. We opened the hatch and found a large rubber hose (facing the rear of the boat) on the left side coming from the engine at a 90 degree angle going to the floor of the boat had cracked and was water began flowing in, causing the steam. Boat was shut down and we were towed back in, afraid to restart it. Could this cracked hose be because of the overheating or is it something different and any addtl items to check for the overheating?

 

[rbh]

Re: OMC 5.8L cracked hose/water leak

rubber hoses get old and should be replaced periodicly.
rob

 

[jmarine225]

Re: OMC 5.8L cracked hose/water leak

i understand rubber hoses get old and need to be replaced eventually but my issued is was the hose just needingt replacement is was/could it be caused by overheating or something else?

 

[Gary H NC]

Re: OMC 5.8L cracked hose/water leak

Is it the big exhaust hose coming off the riser? An overheat will kill those.They blister then leak.
Engine temps near 200 will do it too.It should run 160 to 175 max.
You still have a blockage in the cooling system or the impeller is not pumping enough.
It would be going back to the shop before running again.

 

[jmarine225]

Re: OMC 5.8L cracked hose/water leak

yes it is the large rubber hose. I figured it may be an overheat still and the original problem was never corrected. The engine will start and run but I wouldnt do it as I dont want to cause any more damage. The hose itself appears to be an easy fix but the mechanic said he cannot find the problem which is causing it to overheat. He said he flushed the engine, replaced the thermostat and still can't find the problem. Plus it only goes up to around maybe 190 at most which I know is higher than normal. Any suggestions on what else to do to determine the blockage causing the overheat?

 

[jmarine225]

Re: OMC 5.8L cracked hose/water leak

Also, I sank alot of money into mechanics for the previous repairs. Is it possible to trouble shoot the overheat and repair myself? I have tools but just never worked on boats. But if it's a simple repair such as replacing the exhaust hose I'd like to save myself the $75 an hour charge.

 

[Simoniz]

Re: OMC 5.8L cracked hose/water leak

When the upper unit was replaced, was the impellor new or renewed at the same time?

If the system has been flushed and the thermostat is OK then it sounds like the impellor might not be lifting enough water to keep the engine cool.

A real tell tale of a poor impellor is if you observe steam / water vapour rising from the water behind the boat when its running at low speeds. This is when the impellor cant pump enough water to cool the exchaust and what little water does make into the manifold is turned to steam by the overheated exhaust.

At higher rpms the engine often runs cooler as the impellor then pumps more efficiently and delivers more water.

 

[jmarine225]

Re: OMC 5.8L cracked hose/water leak

when the drive was replaced i had a new impeller put it in also even though there was no damage to the old one but to be safe. I didn't observe any steam or anything at low speed coming from the back. The mechanic said he flushed the entire system and when he did parts of an old impeller were coming out. He said he continued flushing it and nothing else came out but when he ran it again it still was running hot. One of the mechanics said its because the engine is screwed since something is stuck in there. The original mechanic did not agree with that assumption. In the end is this a job I could do myself and at what temperature should the engine be running. It is a 5.8L 351 OMC engine.

 

[jmarine225]

Re: OMC 5.8L cracked hose/water leak

just curious here as the boat is now at the mechanic's. Is there a possibility of hydro locking the engine with a cracked exhaust hose while the engine is running? After the engine was shut down water was still coming out of the hose until we were towed then the water stopped flowing out. Couldn't figure it out. I'm not sure if this engine exhaust has some sort of flappers that would stop water from coming in.

 

[danond]

Re: OMC 5.8L cracked hose/water leak

Find a new mechanic. If he can't troubleshoot an overheating issue, he needs to go back to school.

Also, read your service manual (in the Adults Only sticky in this forum). You own an OMC, so you are at least half of your own mechanic.

1) check impeller flow. Disconnect the inlet that goes to the engine thermostat housing from the outdrive. Fire up the engine on muffs. Does water flow out of the hose? Yes - go to #2. No - replace impeller, check water intake ports on the lower unit for blockage.
2) check all engine hoses. Pull all the rubber hoses from the engine. Look through them, make sure they are clear. Clear? Go to #2. Clogged? Clean them up, re-install, test.
3) check engine cooling jacket. Unscrew all the petcocks in the block. Start the engine on muffs. Does water flow out of each? If no, stick a wire up there and fish it around until the blockage is cleared. If yes, go to #4
4) Check flow into the manifolds. Remove the two hoses going to the manifolds (one hose per exhaust manifold). Does water flow from them when the engine's running on muffs? If yes, go to #5. If no, find the obstruction in the hoses or thermostat housing.
5) Remove exhaust risers. Are they rusty/blocked? If yes, replace them and re-test. If no, go to #6
6) Check exhaust y-pipe for blockage. Remove the outdrive, look into the exhaust bellows for anything blocking water exit. Chunks of exhaust flappers are very common to find. Remove the riser, stick a garden hose into the exhaust pipe on each side and turn the hose on. Water should drain out the outside of the transom. If the pipe fills up, it's blocked.

Finally, replace the circulating pump on the front of the engine. I'm not sure how to test that one. Maybe someone else can chime in.

There's a very, very good chance one of these will be your issue.

 

[jmarine225]

Re: OMC 5.8L cracked hose/water leak

Just wanted to give an update on this situation. After being at the mechanic, again, he found the problem and it was a blockage in the area of the power steering cooler where he found 8 pieces of an old impeller which was causing low power steering fluid and the engine to overheat.
Thanks everyone for your help.

 

[jmarine225]

Re: OMC 5.8L cracked hose/water leak

this is like beating a dead horse but one final question. It appears my overheat is okay now after finding the blockage. Is it possible for the risers to still overheat even though the temp gauge is in a normal range?