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

[Watermann]

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

Good luck buddy! Fingers crossed too.

 

[xadiohead]

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

We spent 8 hours pretty much non-stop on Thursday to replace everything (exhaust manifolds, carb rebuild, water pump, and thermostat). We had to lift engine up a little bit to remove one of the manifolds which took the longest. All said and done with his labor/parts I am at about $1300. Boat started great Thursday night on muffs after he adjusted carb, yesterday on muffs, and this morning on muffs. NO HYDROLOCK!!

My only complaint is the boat was hard to start this morning. I ended up pouring a couple milliliter of gas (very very little) into carb to get it to start. I used to only have to do this a week after I haven't run boat, not the next day. Not sure what to do about this.

But most importantly NO HYDROLOCK! Didn't see any leaks under the engine either. Before I had some from the seeping water pump so hard to tell if water was coming elsewhere.

I am taking it to the lake today for the first time this season (high of 88 today!). Here's to hoping we don't get stranded!

 

[dazk14]

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

We spent 8 hours pretty much non-stop on Thursday to replace everything (exhaust manifolds, carb rebuild, water pump, and thermostat). We had to lift engine up a little bit to remove one of the manifolds which took the longest. All said and done with his labor/parts I am at about $1300. Boat started great Thursday night on muffs after he adjusted carb, yesterday on muffs, and this morning on muffs. NO HYDROLOCK!!

My only complaint is the boat was hard to start this morning. I ended up pouring a couple milliliter of gas (very very little) into carb to get it to start. I used to only have to do this a week after I haven't run boat, not the next day. Not sure what to do about this.

But most importantly NO HYDROLOCK! Didn't see any leaks under the engine either. Before I had some from the seeping water pump so hard to tell if water was coming elsewhere.

I am taking it to the lake today for the first time this season (high of 88 today!). Here's to hoping we don't get stranded!

This should be an easy fix and related to your startup "Technique".

Cold engines require additional fuel to start. Prior to cranking the motor, You should be putting it into neutral (pull out lever, push button, or what have you) and throttling full and pulling back partway - NOT to idle speed.

This will squirt fuel from the accelerator pump(read richen) and engage the temperature controlled choke.

The choke setting will vary on any carb - some do not have a choke , the main thing is that it doesn't stay on too long otherwise it will tend to flood - which is not your problem - good.

You can simply apply more choke - read richen startup fuel mix - by pumping the throttle. This will squirt additional fuel into the engine which is normal and MOST COMMON BY FAR startup problem, meaning not enough fuel.

So, give the throttle an additional pump or 2 - you'll find the sweet spot over time - and crank it up with the throttle opened - NOT in the idle position. You'll have to pay attention when it starts to not over-rev it - which is easy.

Good Luck.

 

[xadiohead]

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

NOOOOOOOOOOOOO!

I changed the oil before we went out today and it was the chocolate milk shake. Didnt see this when I changed the oil a week ago or I wouldn't have spent all the money on the manifolds etc. Put new oil in today, boat ran great at the lake all day, but came home and pumped some oil out and its the chocolate milk.

I am so depressed right now.

 

[dubs283]

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

some of the 4.3's had drains on the front of the intake manifold, 9/16" square plug, if this was not removed at winterize the intake may freeze crack

also, with no visible exterior cracks in the block/manifold the blocks are notorioous for cracking in the valley

 

[xadiohead]

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

Well yesterday I said I had the "chocolate milkshake" but I just said that because thats what everyone refers to it as. But mine really doesn't look anything like a chocolate milkshake. It is actually like a dark olive green color and really smells of fuel really bad. There is no chunkiness, foaminess or anything, and it is very thin.

My oil had a slight fuel smell to it before I had the carburetor rebuilt, but the color appeared good. Not the color is really weird.

I tried to duplicate the color by mixing new oil with water, fuel, water/fuel combo, and even tried boiling all these combinations. Couldn't get anything close to the olive green color.

I realize all signs are pointing to an internal cracked block but this just confuses me.

Any thoughts?

 

[skier-24]

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

some of the 4.3's had drains on the front of the intake manifold, 9/16" square plug, if this was not removed at winterize the intake may freeze crack

also, with no visible exterior cracks in the block/manifold the blocks are notorioous for cracking in the valley

Any pictures of "cracking in the valley"? Not wanting to hijack the thread but I am also having an issue with a 4.3 causing runnability issues.

 

[ricohman]

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

Well yesterday I said I had the "chocolate milkshake" but I just said that because thats what everyone refers to it as. But mine really doesn't look anything like a chocolate milkshake. It is actually like a dark olive green color and really smells of fuel really bad. There is no chunkiness, foaminess or anything, and it is very thin.

My oil had a slight fuel smell to it before I had the carburetor rebuilt, but the color appeared good. Not the color is really weird.

I tried to duplicate the color by mixing new oil with water, fuel, water/fuel combo, and even tried boiling all these combinations. Couldn't get anything close to the olive green color.

I realize all signs are pointing to an internal cracked block but this just confuses me.

Any thoughts?

Put the oil in a glass container and let it sit. You will know by the next day if there is water in it. Fuel in the oil won't do this. You could have a crack somewhere. Draining and pouring in antifreeze is a good way to crack a block. Nobody does that where I live and its -40 all winter.

 

[xadiohead]

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

Put the oil in a glass container and let it sit. You will know by the next day if there is water in it. Fuel in the oil won't do this. You could have a crack somewhere. Draining and pouring in antifreeze is a good way to crack a block. Nobody does that where I live and its -40 all winter.

The oil sat for over 24 hours and had time to separate. Here are a couple pictures: https://www.dropbox.com/sc/db3cduv6bxoo1ld/d8m83B3ggx



I do not understand your comment about pouring antifreeze as a good way to crack a block. How is that possible?
The mercruiser manual says to pour antifreeze down the hoses. I recently noticed that I poured antifreeze down 3 hoses off the t-stat housing: hose to left manifold, hose to right manifold, and intake hose (when I poured it in it went out the lower unit muff holes). So really no antifreeze would have gotten into block. The antifreeze was hardly in the boat very long. I just poured it in to help dilute any water and the manual said to. I then pulled all five plugs.

 

[ricohman]

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

The oil sat for over 24 hours and had time to separate. Here are a couple pictures: https://www.dropbox.com/sc/db3cduv6bxoo1ld/d8m83B3ggx



I do not understand your comment about pouring antifreeze as a good way to crack a block. How is that possible?
The mercruiser manual says to pour antifreeze down the hoses. I recently noticed that I poured antifreeze down 3 hoses off the t-stat housing: hose to left manifold, hose to right manifold, and intake hose (when I poured it in it went out the lower unit muff holes). So really no antifreeze would have gotten into block. The antifreeze was hardly in the boat very long. I just poured it in to help dilute any water and the manual said to. I then pulled all five plugs.

Sorry I cant see the pics well enough. They are dark and my old CRT monitor is dark to begin with.
When you pour antifreeze into the engine you risk diluting it with any water left in the block due to plugged drain ports ect. Then you end up with a large amount of diluted antifreeze that will turn into a solid at far warmer temps than -40. Maybe minus 10? Who knows.
Then come spring you have a cracked block.
I read that antifreeze thing in my brand new 4.3 manual two years ago. Needless to say I never followed that advice. Like bondo is always saying, "air don't freeze".
I bet antifreeze in the number one cause of cracked blocks come spring.
But then you haven't full diagnosed this yet and you don't really know what you have. It may be time to start pulling the intake and heads though. Then you will know if its leaking up top.

 

[dubs283]

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

I then pulled all five plugs.

did you check to see if there is a plug in the front of the intake manifold??

 

[Watermann]

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

Maybe you could try doing a pressure test and find where the air is coming from before ripping into the motor.

 

[xadiohead]

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

When you pour antifreeze into the engine you risk diluting it with any water left in the block due to plugged drain ports ect. Then you end up with a large amount of diluted antifreeze that will turn into a solid at far warmer temps than -40. Maybe minus 10? Who knows.
Then come spring you have a cracked block.
I read that antifreeze thing in my brand new 4.3 manual two years ago. Needless to say I never followed that advice. Like bondo is always saying, "air don't freeze".
I bet antifreeze in the number one cause of cracked blocks come spring. .

Just checked the weather records and it never got below about 5f here in Oklahoma and I drained the antifreeze after I poured it down those hoses. Again I don't think any made it to the engine based on where I poured it. I did read the whole "air doesn't freeze" thing back in October which is why I left the five plugs out all winter. I even pushed a screwdriver up to make sure there wasn't a blockage like the manual says to do. Also keep in mind my boat was stored inside a small brick external garage with a space heater set to 39 degrees. I realize the space heater is not a tried and true method and can turn off during power outages, but it was just a backup. .... So you just pull the plugs and don't mess with antifreeze?

did you check to see if there is a plug in the front of the intake manifold??

I did not check this yet as I'm not really sure what exactly the intake manifold entails. After searching, it looks like it is what the carb connects to? If thats the case, how would it freeze if it doesn't have water going through it? (I'm a novice so bare with me!)

The manual I have says there are only five plugs to drain and says nothing about the intake manifold.

Maybe you could try doing a pressure test and find where the air is coming from before ripping into the motor.

Can you please point me in the right direction on how to do this?

 

[dubs283]

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

I did not check this yet as I'm not really sure what exactly the intake manifold entails. After searching, it looks like it is what the carb connects to? If thats the case, how would it freeze if it doesn't have water going through it?

yes the intake is what the carb is mounted to, and if equipped with a drain plug its located on the front vertical face of the manifold behine the belt(s). its a square head pipe plug painted black so you'll need a flashlite

water does pass through the manifold and some designs allowed water to collect in the lower portion hence the drain

 

[ricohman]

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

I can see those pics now. Thats water for sure. Every day you let it sit you will see more separation.
And yes, thats all I do. Drain out the water and put it away. I don't mess around with antifreeze.

 

[xadiohead]

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

Again, all I did tothe block was drain the two plugs and left them out all winter. I remember water came out both drains when I pulled them. Boat was on trailer and might not have drained all the water?

So to pressure test the water jacket, will this work:
1) Loop a hose on the t-stat housing from both exhaust manifold ports. Basically to plug the ports and remove the exhaust manifolds from equation.
2) Remove incoming water supply line off t-stat housing (this port will be used for air pressure)
3) Install short hose to t-stat housing supply port with pressure gauge tee
4) Connect compressor to the tee and pressurize to 15psi.
5) Wait to see if pressure drops and listen for leaks

If the above will work, how careful do I have to be in order to not over pressurize?

 

[Watermann]

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

Looks like you found a good reference for the pressure test. Yeah don't shoot much pressure over 12 psi into the system.

Earlier you said you pulled 5 plugs, my 4.3 has 4 drain plugs, 1 on each exhaust manifold and 1 on each side of the engine block. Then I pulled all the hoses to let the water out of them. Your last post you said you just drained the block, I wonder if not taking the hoses off could have let some water stay inside, just a thought. Where is the 5th plug you talked about?

 

[xadiohead]

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

Earlier you said you pulled 5 plugs, my 4.3 has 4 drain plugs, 1 on each exhaust manifold and 1 on each side of the engine block. Then I pulled all the hoses to let the water out of them. Your last post you said you just drained the block, I wonder if not taking the hoses off could have let some water stay inside, just a thought. Where is the 5th plug you talked about?

Wish I would have understood how easy it was to pressure test the block. I would have done that before spending $1300 on manifolds and card rebuild. Going to try to get to it tonight.

Anyhow, I have one drain plug on each exhaust manifold (2), one drain plug on each side of block (2), and then one plug in bottom of hose connecting water pump to t-stat housing (1) to make five total.

In terms of hoses, after I poured antifreeze down them, I pulled both exhaust manifold hoses and the water supply hose off the t-stat housing. I left the water pump to t-stat housing hose in place because it has a drain plug.

Something the manual says to do is to "bump/crank" the engine (without starting) for a couple seconds after you have done everything in order to drain any water sitting in water pump. I did this, but now that I think about it, wouldn't it just send any remaining water into the engine?

 

[xadiohead]

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

Okay I just wasted three hours going to stores trying to come up with a contraption to pressure test my block using my steps above. You guys must be way smarter than me because I am going freaking crazy. How on earth do you connect a tee for a pressure gauge and a compressor to the t-stat housing given the size? It is about a 1.25" hose connection or so. Compressors and gauge ports are all tiny compared to this. Please somebody help me out. Here is a picture

https://www.dropbox.com/s/dak8foo2xeqqq2u/2014-05-06 18.59.41.jpg

 

[Watermann]

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

The attachment pic isn't working.