do exhaust manifolds cause engine water problems?

[shelikesit]

First off, thanks DonS for the advice on the merc manual for my engine, it came today. I have to get the sterndrive one next.<br /><br />Now the boat - 1990 4.3 V-6 Eng # 0C766244 that sat for a long time. I'm having the same problem as tashasdaddy with the milkshake oil from ugly sludge buildup. I will be on my second oil change tomorrow morning and will probably do another when I come in. Am thinking about the quart of diesel as Don suggested to tashasdaddy also. I'm using seafoam now.<br /><br />Just had the carb rebuilt and fixed a few air leaks and took it out today but couldn't get it to power up. I made it back and changed the plugs at the dock and as soon as I went back out and was out of the no wake zone hitting throttle - cylinder #'s 3 and 5 fouled wet.<br /><br />I had to replace valve covers last month and when doing so I saw the rust on the inside of the exhaust manifolds. Would this crud be on the inside channels also causing water to back up into my cylinders. Or would it be the head gasket. I'd say gasket but the motor side of the manifolds were pretty bad.<br /><br />Only test that I saw in the manual for a blown head gasket was clear plastic tubes hooked to the water ports looking for air bubbles, is there another test for the head gasket? Manual said a compression test isn't reliable for the head gasket.<br /><br />The engine is not overheating for some reason.<br /><br />Sorry about the questions congumbled but I'm trying here..........

 

[tashasdaddy]

Re: do exhaust manifolds cause engine water problems?

dan do you have the one piece batwing manifold or the 2 piece? i've been trying to change to a 2 piece with no success.

 

[Don S]

Re: do exhaust manifolds cause engine water problems?

If you are getting water in the cylinders while running, it could very well be the manifolds, or a head gasket.<br />You could isolate the engines cooling system and pressure check it. If it doesn't hold pressure then you have a leak and it has to be located. If you pull the spark plugs you should be able to hear the air leaking into the cylinders. But if you have rust in the exhaust ports of the exhaust manifold and it's running down from the riser/manifold connection, then it's probably time to replace them.

 

[shelikesit]

Re: do exhaust manifolds cause engine water problems?

Thanks again Don...........<br /><br />Today I changed the filter above the fuel pump and flushed water through the drain ports on the manifolds. A good bit of sandy crud came out and I thought this would of freed up the water passages.<br /><br />It didn't. I changed the plugs and it fired right up. It ran fine without a miss on the trailer. Took it off the trailer and pointed it outward. It did fine once again until I hit the throttle. Then it dogged down and seemed as though it was choking out again. Got it to the dock and # 3 and # 5 plugs were soaked with water again.<br /><br />All the rest of the plugs are dry as a bone. What gives...........<br /><br />Start with the exhaust manifold or do that and the head gasket at the same time?<br /><br />Is there a way to test for the head gasket alone?<br /><br />Personally I think the manifold is backwashing into the cylinders on that side. According to the troubleshooting chart this is very possible.<br /><br />Tashahsdaddy, I didn't forget you, mine are 2 piece manifolds, if I could of gotten the gaskets this morning I would have the port side in pieces.<br /><br />For some reason only west marine is open today..........

 

[Don S]

Re: do exhaust manifolds cause engine water problems?

Like I said, pressure check the cooling system of the engine. Plug off the hoses going to the exhaust manifolds, and any other outlets, disconnect the inlet hose and make an adapter to fit and pressureize it. If it holds pressure, it's not the head gasket.<br />All the rust coming out of the exhaust manifold is mostly from the manifold. Also check the manifolds where the gaskets go. They need to have good metal, not black hard carbon doing it's best to imitate metal where shown in the drawing below.<br />If you can scrape those areas away with a stiff scraper, the manifolds are junk. That black stuff has caused more than one engine failure.<br /><br />

 

[shelikesit]

Re: do exhaust manifolds cause engine water problems?

Does this make sense or will and won't it destroy the manafold gasket??? I'm trying to start with the manifolds. Seems like I should do what Don said first if this below ruins the gaskets.<br /><br /> Go to the hardware store and buy two bolts about 1" longer than the ones which hold the manifolds onto the head of your mercruiser. replace the two outer bolts with these bolts, then remove the other bolts holding the manifolds in place and slide the manifold back on the outer bolts to create a space between the head and manifold. Put city water pressure in the feed hoses to the manifold and look into the crack between the manifold and head. If the manifold fills up and drips out toward the engine then either the manifold or elbow is broken. Repeat on other side if you have V engine manifolds.

 

[tashasdaddy]

Re: do exhaust manifolds cause engine water problems?

dan, it makes sence to me but lets see what the group says.

 

[tashasdaddy]

Re: do exhaust manifolds cause engine water problems?

dan, it makes sence to me but lets see what the group says. i'm sure you would still have to replace the gasket.

 

[shelikesit]

Re: do exhaust manifolds cause engine water problems?

To think I just found 2 bolts long enough to do this test. 5 minutes before autozone closed on Christmas Eve.<br /><br />I had to buy 2 help packs. Each pack had a bolt long enough to use, cost per pack - 5 bucks.<br /><br />Hope the wife goes to spend time with her kids tomorrow

 

[markvictor]

Re: do exhaust manifolds cause engine water problems?

Also important as well as checking the surface between the water ports and the exhaust port on your manifold..Look in the centerport...should be carbon only...water and rust in the center port are a definitive indication that your are introducing water into your cylinder(s)...The fact that it is the #s 3 and 5 cylinders is a good reason to suspect<br />the manifold, as they are at the mid and low pointand adjacent.<br />Therefore, if the gasket surface appears good,you may still have a bad manifold or riser...And you did not mention if you have 1 or 2 piece manifolds...The one piece needs to be looked at top and bottom to inspect properly...which is best done off the engine...

 

[KaGee]

Re: do exhaust manifolds cause engine water problems?

Hey guys, check THIS out.