4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

xadiohead

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This is long/detailed. First thing I will say is I have literally googled hours upon hours regarding this. I rarely post but figured I would see what help/suggestions I can find out. Next thing I will say is I clearly made some very stupid mistakes with this boat, I realize now how dumb some of these decisions were, but at this point just looking to see how I should move forward.

Two years ago I bought a 1999 tahoe with 4.3 merc. A year ago the boat seemed to be overheating a bit. It still ran fine so I ignored it (dumb). Then a month or so later it hydrolocked on me because I killed the engine while going about 20mph (dumb). I had my friend who is good with boats help me out. There didn't appear to be any damage done during the hydrolock but while looking at it he realized the left manifold was getting EXTREMELY hot and a little steam was coming up. We ended up removing the thermostat altogether and replacing manifold gaskets and problem seemed solved. I was supposed to get a new thermostat but never did (dumb). Boat ran great rest of summer (about 20 days).

Winter storm snuck up on me. My friend wasn't available to winterize and shops were too busy due to so many people needing boats winterized before early storm. So I winterized it myself. I pulled the 5 plugs (3 on block, 2 on manifolds) poured antifreeze down most of the hoses, ran fuel stabilizer, changed most of the oil (it was cold so hard to pump all out), changed water separating filter, oil filer, removed spark plugs and sprayed fogging oil in them. I then stored the boat in friends small brick external garage with space heater set at 39 degrees all winter. The main thing I failed to do was run the 5 gallon of antifreeze through the exhaust like everyone says to do (dumb). I left 5 plugs and several of the hoses disconnected all winter (dumb?). Last thing to note is that one of my "new" left manifold gasket fell out while winterizing. I live is Oklahoma and we did have a pretty rough winter.

Moving now to last week, I hooked everything up and it started fine. Ran it for a couple minutes on muffs, was happy. Wanted to start it one more time after washing it before taking it to where I store it: hydrolocked. I won't go into details but I naively thought it was related to car wash. I pulled the plugs, hand cranked flywheel (didn't really see any water come out), put plugs back in and it started great. Ran it for a few minutes on muffs . Turned it on and off a couple times, reved it, ran perfect. Next day went to start it before taking it to storage and hydrolocked. I again pulled plugs (one on left side was fouled), sprayed marvel mystery oil in holes, hand cracked and again didn't see any water come out. Thats how I have left it. There appears to be water in the oil as the dipstick is really high. I did pump out about 2 cups worth but couldn't tell any discoloration or milkiness.

I just went and inspected it using a mirror, i don't really know where all to look but I didn't see any cracks in block (from where I can see). I did however see a pretty good crack in the water recirculating pump. This obviously needs to be replaced.

Earlier this week we very randomly got down to 32 degrees so I went ahead and pulled the 5 plugs just to be safe. Zero water came out of the left manifold. None. These are the original manifolds (15 years old) and after googling realize they need to be replaced.

I realize given the timing, all signs point to cracked block. But given my overheating last summer, cracked water circulating pump, and apparent issues with the left manifold (including missing gasket), I am wondering if this might be something besides cracked block.

My next step is waiting on boat friend to come do compression test with his gauge he plugs is spark plug holes.
 

Fun Times

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

I left 5 plugs and several of the hoses disconnected all winter (dumb?).

Last thing to note is that one of my "new" left manifold gasket fell out while winterizing.

My next step is waiting on boat friend to come do compression test with his gauge he plugs is spark plug holes.
Hi there, welcome to iboats!:) Sorry to hear of your engine troubles, hopefully we'll be able to help guide you and your boat friend through some sort of resolution.

An engine compression test is definitely in order and a cylinder leak down test would be a good idea to as you may have a head or head gasket problem or intake manifold or gasket problem or both due to overheating.

Would you be able to elaborate a bit more on how the exhaust manifold gasket fell out while winterizing? I'm not really clear on that.

As long as you know all the water is out of the engine block and exhaust system by sticking something small like an old phillips head screwdriver into each hole to ensure the water is able to be drained due to blockage, then there is nothing wrong with leaving the plugs and hoses out/off.

To help test to see if the cylinders are building water, it's easier to turn the engine over using the engine starter. Just block the area around spark plug holes with cardboard so the sides of the boat don't get wet/dirty when the water sprays out.

If you want to see if your oil is milky, just blow some air down the dipstick tube mixing the two up, you will hear some bubbles then recheck your oil.
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Thanks for the response. In regards to the manifold gasket coming loose: from what I remember the gasket was sold as three separate pieces that went between the manifold and the block. They basically just slide into place. One of them fell out. Not sure how.

We just did the compression test. All cylinders had between 180-200psi with the majority being right at 180.

We then went ahead and put everything back in (hoses, spark plugs, drain plugs), hooked it up to water and let it run for about 5-10 minutes. Neither of the manifolds was getting too hot. Lukewarm at best which seems to be a good sign.

After it ran, I took out the left manifold drain plug and water gushed out this time, so not sure why water wasn't in there earlier this week.

While the engine was running he constantly pulled the oil stick looking for any indicators. Occasionally there was a very very small particle, but other than that he said it was fine.

He said it was slightly possible it could be extra unburn fuel piling up into a cylinder and not water. So about 20 minutes later we restarted the engine and let it run for another five minutes or so. While running he pulled each spark plug wire off (immediately put each one back on afterwards). After each wire was disconnected, you could tell a difference in the engine running on 5 cylinders, which he said was a good sign.

He's not a full time mechanic by any means, just very good with engines, especially boats. He said he doesn't think it is a cracked block but also couldn't rule it out. Same with head gaskets.

So I still don't know what to do! I am going to leave it overnight and see if it hydrolocks tomorrow.

Any more suggestions?
 

Bondo

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

A year ago the boat seemed to be overheating a bit.

Ayuh,..... Welcome Aboard,.... To go along with FT's tips,...

Change out the Impeller in the drive too,....

That's Always the 1st thing to do in Any overheat situation,...
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

To help test to see if the cylinders are building water, it's easier to turn the engine over using the engine starter. Just block the area around spark plug holes with cardboard so the sides of the boat don't get wet/dirty when the water sprays out.
.

Can you further explain how and what this is doing? So I should have no spark plugs in there, and put a piece of cardboard over the holes? Then when you say use the engine starter, are you talking about turning the flywheel manually or turning the key?

Bare with me, a year ago I had no clue how to replace spark plugs (I can do all six now in under 30 minutes!)


I actually joined this site two years ago, I just finally posted an issue. I've had my fair share, I've just been able to search for all my solutions.
 

Fun Times

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Do you have your engine serial number handy so we can find you the correct engine parts for your engine model? The exhaust gasket design dose not sound familiar to me.

Do you know if you have a one or two piece exhaust system? The one piece have been known to cause some issues in the past.

No other signs of water in the oil? May want to change the oil and the filter again to be sure.

Now that you ran it, pull the spark plugs again before starting to see if you have any more water.

Good luck.:)
 

Fun Times

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Can you further explain how and what this is doing? So I should have no spark plugs in there, and put a piece of cardboard over the holes? Then when you say use the engine starter, are you talking about turning the flywheel manually or turning the key?

Bare with me, a year ago I had no clue how to replace spark plugs (I can do all six now in under 30 minutes!)


I actually joined this site two years ago, I just finally posted an issue. I've had my fair share, I've just been able to search for all my solutions.
You need to know visually if you are still getting water into the cylinders or not. It could be a little or it could be a lot. You need none. To test, lower the stern drive, hook up the water flush kit (muffs) to the stern drive, remove the spark plugs, shove some type of cardboard next to the plug holes under the exhaust manifolds, For safety remove the purple wire off of the + side of the ignition coil, turn on the garden hose water to full, then using the ignition key crank over the engine for 10-15 seconds then go see if the area down by the spark plugs holes are wet. If your friend is there have them watch to see how much water is coming out and go from there.

Let us know your findings and good luck.:)
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

I will have to search for the engine serial number. I bought the gaskets from an automotive store.

I am almost certain it is a one piece exhaust, keyword almost.

We ran it a total of about 16 minutes (two times of eight minutes) and didn't see any signs of water in the oil. We checked the dip stick probably 20 times and there was no milkiness anything like people describe. My friend said he knew what to look for and had seen the water in oil many times.

Yes I definitely plan on putting new Mercruiser oil and filter on if it doesn't hydrolock tomorrow. Same with plugs. Just going to put new plugs in. Its worth the $25 to me to know.
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

I wasn't able to find a serial number.

I decided I wanted to go ahead and change the oil. I just pumped two quarts of oil out and I smell FUEL in it! My assumption is the fuel hydrolocked the engine and not water. All the research I've done over the passed week was based on water hydrolock so I need some help/suggestions. I do know I need to drain and replace the rest of the oil before running engine again which I will do tomorrow.

One other thing I never mentioned (and could now be relevant) is my carburetor doesn't seem to be in very good condition. Last year, each week when I would go to start the boat it would take me a couple minutes to finally get it started. Once it started I was good until my next trip.

I know fuel in oil isn't good by any means, but it appears to be better than water?

Does this help reduce chances of this being a cracked block?
 

Fun Times

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

I wasn't able to find a serial number.
See if this helps with the serial number. http://forums.iboats.com/non-repair...engine-serial-numbers-630103.html#post4398826

I decided I wanted to go ahead and change the oil. I just pumped two quarts of oil out and I smell FUEL in it! My assumption is the fuel hydrolocked the engine and not water. All the research I've done over the passed week was based on water hydrolock so I need some help/suggestions. I do know I need to drain and replace the rest of the oil before running engine again which I will do tomorrow.

One other thing I never mentioned (and could now be relevant) is my carburetor doesn't seem to be in very good condition. Last year, each week when I would go to start the boat it would take me a couple minutes to finally get it started. Once it started I was good until my next trip.

I know fuel in oil isn't good by any means, but it appears to be better than water?

Does this help reduce chances of this being a cracked block?
If your thinking it's fuel and not water then you'll need to test the fuel system and check to see if your carburetor seems to be pouring extra fuel into the intake manifold while the engine is off. Have a look at this thread by forum member JustJason on how to go about checking your fuel system. http://forums.iboats.com/mercruiser...ow-testing-your-boats-fuel-system-283269.html

You may have something like a stuck open needle and seat inside the carburetor allowing to much fuel flow. Can you get a photo of your carburetor and exhaust manifolds as they offered two styles in and around 1999.

Unfortunately it's hard for us to say how bad your engine is damaged if any since were not there looking at it, about all can do is inform you of the possibilities that may have happened from your descriptions above.

Going by how you winterized the engine, it don't seem like you cracked the block over the winter if you did it in time before the real cold hit and it was completely drained of water.

Overheating would put water in your cylinders.

And over fueling from the carburetor or fuel pump would hydrolock the engine.

Again my test above may help tell you what and how much is coming out of the cylinders by looking and smelling.

You need to verify if it's water or fuel or both as from you descriptions, it could be either or.

If you can't tell what's spraying out of the cylinders at cranking speed, then you need to ready to pull the spark plugs for when the next time it hydrolocks and see what's on the spark plugs, gas or water.
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Before I ran anymore tests, I wanted to see if it would hydrolock again. Last week it was hydrolocking after hours of sitting. So I put new oil in and also added ATF to power steering as it was completely empty and making a noise. Boat then started and ran great (with muffs). There didn't appear to be any increase in the oil level when I was checking.

I then decided to go ahead and install new spark plugs. She ran great again. I let it run for maybe 6 minutes on mufss. Manifolds weren't getting very hot. Oil appeared good. No issues.

So at this point I am hoping it was isolated incidents and I have fixed the problem. If it happens again, then I will do all the testing from JustJason.

Here are my next steps:
1) Replace water recirculating pump
2) Install new thermostat
3) Buy and install new manifold gasket that came out (I will take pictures of the gasket and my manifolds)
3) Look into having carb worked on

Sound good?
 

Fun Times

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Here are my next steps:
1) Replace water recirculating pump
2) Install new thermostat
3) Buy and install new manifold gasket that came out (I will take pictures of the gasket and my manifolds)
3) Look into having carb worked on

Sound good?
Yep, sounds like a plan. Also while your working on the boat, you really should consider changing out the rubber impeller located in the stern drive as that is a vital cooling component that is sensitive. You need to know it's condition and that it's not going to go out on you anytime soon.
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Well not as lucky as I was hoping. Just like last week I went to start the boat today to make sure I was still good. It immediately hydrolocked. I cringe every time I turn the key hoping to not hear that sound.

So I pulled the plugs and immediately TRIED the cardboard thing. But I just realized i tried it without the boat on muffs (I never start the boat without muffs, just did it because I was only cranking). The sides of my engine are pretty difficult to access and really hard to put cardboard flush with the holes but I did my best. Don't have anyone around to help now. I did the test three times, each for about 8 seconds. I never saw anything on the starboard cardboards. The second time on the port side there appeared to be a little fluid towards the middle hole but nothing the other times. When I am shoving the cardboard there, I could be rubbing against water from a hose I had to disconnect for access etc so not positive it is from the hole. I realize I need to redo this with muffs.

I took a few pictures. The spark plugs were brand new and only ran once yesterday for about 5 minutes. Here is a link to the pictures:

https://www.dropbox.com/sh/nywzvrwgwylsnaq/XV168mfYJT


A couple of the plugs seemed to have a fuel odor but was pretty hard to tell.

Also, JustJasons guide says it "assumes the fuel pump and carburetor are working properly." This is confusing on how this will help be diagnose if I have a bad carb.

Thanks again
 

Bondo

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Ayuh,..... Those 1pc manifolds are a Known Failure point, they're Junk the day they were built,....

Get yerself a set of manifold/ risers, 'n convert yer's,to the 2pc set-ups,...
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Bondo- thanks for the info on the 1 piece manifolds. I've been reading that manifolds in general only have about a 10 freshwater life cycle. I don't want to put anymore money into this boat until I know what is causing this hydrolock issue and that it is fixable. Once/if I get everything running, that will be my next fix.


Just tried cardboard test again but this time with water in muffs. Ran two tests. The first test there was a very small liquid spec on the middle starboard side. The port side didn't appear to have anything either time. Again, t's difficult for me to get the cardboard in there perfectly and that spec could have been from me rubbing the cardboard on something when shoving it in there. I understand I need no liquid at all in the cylinders, but I would think this test should rule out a significant amount of liquid. Especially since I couldn't get two common incidents.

This appears to be caused by PRESUMABLY fuel building up in cylinder(s) with the boat sitting for at least several hours. Two of the occasions were the following day and another was 3-4 hours later. Whats your best guess on the most likely suspect of this? The JustJustin thing my best next step? Looks a bit overwhelming and I'm still wondering if its related to carb.
 

Watermann

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

The steel manifold gasket that fell out was supposed to me put in with the 'hooks' over the top of the studs going into the head. The fact that it "fell out" means that the bolts weren't torqued down, backed out and allowed the gasket to simply fall out.

The upper right spark plug in the pic looks to me to be steam cleaned meaning that water could be getting into the cylinder not allowing the normal deposit of carbon to be present from the combustion process.

Not sure how you can stand to run the motor if that gasket wasn't replaced, it would be leaking exhaust and lots of noise.
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

I kinda watched my friend install those gaskets last summer and it was not an easy task to unbolt/bolt the manifolds due to engine compartment. Guess he just didn't get it tight enough like you said. Engine doesn't seem any louder and can't sense any exhaust. I will buy another one and try to install it. I'm pretty sure this gasket is unrelated to my hydrolock issue.

So lets say I get everything running tonight and it hydrolocks on me tomorrow. Could I only pull that upper right spark plug and then try to start it? I assume an engine will start on 5 cylinders. Is this a bad idea/test? All three times it has hydrolocked I haven't once tried to restart the engine until pulling plugs. I hate to try to start it in risk of damaging rod, etc.
 

Bondo

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

Bondo- thanks for the info on the 1 piece manifolds. I've been reading that manifolds in general only have about a 10 freshwater life cycle. I don't want to put anymore money into this boat until I know what is causing this hydrolock issue and that it is fixable. Once/if I get everything running, that will be my next fix.


Just tried cardboard test again but this time with water in muffs. Ran two tests. The first test there was a very small liquid spec on the middle starboard side. The port side didn't appear to have anything either time. Again, t's difficult for me to get the cardboard in there perfectly and that spec could have been from me rubbing the cardboard on something when shoving it in there. I understand I need no liquid at all in the cylinders, but I would think this test should rule out a significant amount of liquid. Especially since I couldn't get two common incidents.

This appears to be caused by PRESUMABLY fuel building up in cylinder(s) with the boat sitting for at least several hours. Two of the occasions were the following day and another was 3-4 hours later. Whats your best guess on the most likely suspect of this? The JustJustin thing my best next step? Looks a bit overwhelming and I'm still wondering if its related to carb.

Ayuh,.... Smell, 'n taste the liquid,.... I doubt it's Gas,....

Pull that manifold off, 'n Look for rust tracks,....
 

xadiohead

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

There was too little of liquid on the cardboard to smell or test.

I just hooked everything back up and to no surprise it ran great. Started it about fives times and ran a total of maybe five minutes. Same thing, manifolds not getting hot (the starboard side is lukewarm, the other can't feel any warmth). Didn't see any issues with oil.

In regards to pulling the manifold(s), it will be very difficult given the design of my boat. There is not much room to get bolt off:
https://www.dropbox.com/s/7222wr2649nhie5/1 2014-04-20 20.33.45.jpg

That is something I would have to wait until next weekend to attempt :(

So frustrated.
 

Bondo

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Re: 4.3 merc Cracked block, blown head gasket, or manifods? (LONG)

There was too little of liquid on the cardboard to smell or test.

I just hooked everything back up and to no surprise it ran great. Started it about fives times and ran a total of maybe five minutes. Same thing, manifolds not getting hot (the starboard side is lukewarm, the other can't feel any warmth). Didn't see any issues with oil.

In regards to pulling the manifold(s), it will be very difficult given the design of my boat. There is not much room to get bolt off:
https://www.dropbox.com/s/7222wr2649nhie5/1 2014-04-20 20.33.45.jpg

That is something I would have to wait until next weekend to attempt :(

So frustrated.

Ayuh,.... If workin' on boat motors was Easy,....

Everybody would be doin' it,....

I've seen over 1/2 dozen motors Destroyed by those manifolds, that were supposedly in Perfect condition,...
 
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