Mercruiser 7.4 MPI Valve Job . . .

[alldodge]

Boat budget is looking pretty sick this year . . . Based on all the projects and regular maintenance that I have lined up.

I try real hard to tell the admiral that she looks real good on the boat and could be a real impact if not fixed soon If we didn't go on te trip to see her mother it would be OK and we could save the funds to help fix the issue. :facepalm: I never get away with that one but I have to try

Totally understand the budget, I've been planning my repower for a while, but didn't plan on the transom

 

[Volphin]

I've noticed that there are also a lot fewer machine shops in my area. I don't know if that is a trend nationally, but it sure limits your choices. I was lucky to find one that specializes in racing heads and does regular machine work as well.

AllDodge, I'm STILL laughing at your post. I'm gonna try that one. Probably with the same results though...

 

[tpenfield]

I've noticed that there are also a lot fewer machine shops in my area. I don't know if that is a trend nationally, but it sure limits your choices. I was lucky to find one that specializes in racing heads and does regular machine work as well.

AllDodge, I'm STILL laughing at your post. I'm gonna try that one. Probably with the same results though...

Yea, I did find the shop that I had used a few years ago for some previous work, but there seems to be only a few shops that you can find online. Probably some others without web presence though.

The boat budget is always an interesting topic with the Admiral, especially since we have 2 kids in grad schools. I guess tuition and living expenses come first? :noidea:

Anyway, I had visions of buying a sailboat to have as a windy day boat, but between the funding and available time, that is not going to happen for a while.

 

[Scott Danforth]

Ted, for what it's worth, I just dropped off the head for the daily driver due to a departed head gasket to a cylinder head shop here in Clearwater. $100 gets you an inspection, cleaning, and surfacing. they have same day turn-around

http://www.cylinder-heads.com/

 

[tpenfield]

Update:

I did the 'snake oil' thing on the engines today, just to see if and what sort of difference a little bit of combustion chamber cleaning makes on the numbers.

So, I picked up 4 cans of Seafoam and did the treatment.

Rather than pouring the seafoam into the air intake as typical instructions indicate, I mixed a 50/50 solution of seafoam and regular gasoline totaling 1 quart. Then I hooked my 'mix' to the fuel line and ran it thru the fuel system (MPI) until it had drank most of it.

Then I turned off the engine(s) and disconnected the ignition wire and cranked the engine for several 7-8 second 'blasts', figuring it would basically flood the engine/cylinders.

I let the engine(s) sit for about an hour and then started them back up, now connected to the regular gas/fuel line. I revved the engines up a bit maybe hit 4K a couple of times.

Then I kept the engines rev'ed at about 2500 RPM and induced a slight spray of water into the intakes - this essentially will perform a second 'steam' cleaning of the combustion chambers. So, I gave it about 5 minutes of water, then ran as normal for another 5 minutes or so.

After that was all said and done, I ran another compression test. Hear are the numbers:

Port Engine: Before/After

1= 137/129
3= 129/123
5= 126/122
7= 135/131

2= 140/138
4= 134/126
6= 133/127
8= 140/130

Starboard Engine: Before/After

1= 125/126
3= 124/126
5= 118/122
7= 117/122

2= 124/127
4= 128/125
6= 127/120
8= 128/130

Anyway, it looks like the Starboard engine was a little higher after the combustion chamber cleaning and the port engine was a bit lower. I think I am going to leave things alone for the time being. Maybe give it further consideration for next year.

 

[alldodge]

Over all it just looks like you have some tired engines, nothing that won't keep running for a while. Maybe as you say just run them a bit longer until they start to groan a bit more

 

[Bondo]

Over all it just looks like you have some tired engines, nothing that won't keep running for a while. Maybe as you say just run them a bit longer until they start to groan a bit more

Ayuh,.... Unless ya got an extra 10 Grand burnin' a hole in yer pocket, I wouldn't worry 'bout puttin' some more hours on 'em,.....

 

[tpenfield]

Yea, AllDodge & Bondo, I tend to agree with both of you. The engines are not bad at all and it may be worth running them for a few more years and then do both top and lower ends. I'll have to start the 'engine rebuilding fund' . . .

They do sound pretty awesome rev'ing up into the 4 K range - smooth. :thumb:

 

[Volphin]

Fairly even numbers! They may be tired, but I'd run the heck out of them. Hmmmm. I wonder if they are low enough for some nice roots SCs? MOOOO HAHAHA!

 

[tpenfield]

Yes a little super charging might be nice, but . . . .

Since I have decided to run the engines for a little longer 2-3 years :noidea: , I thought that I would get an 'mini' inspection camera (endoscope) to take a look at the combustion chambers and valve seats, since I won't be seeing them for real until I take the heads off of the engines.

So, I ordered a "USB 5.5 mm diameter borescope/endoscope" online this morning. It hooks up to a laptop so I can get pictures or even video. Also comes with a right-angle mirror to see more angles. I figured that 5.5 mm -should- fit into the spark plug hole, which I believe is about 7 mm.

I currently have a 9 mm inspection camera, but that did not quite fit into the spark plug hole, so I could not see much.

Anyway, once I get the new 'toy', I'll probably take a look at the combustion chambers to get an idea of how things look after the 'cleaning' that I did. It should be kind of cool being able to see things that you would normally have to remove the cylinder head to see.

 

[Scott Danforth]

borescope engine porn

 

[tpenfield]

borescope engine porn

I'll post some as I get it . . .

 

[NHGuy]

If you DO end up working the heads I have business experience with Brittons in Beverly, MA on lots of car engine heads. Never a hiccup. I know Cape Cod is a long way from Cape Ann but they are good.
My nephew is a full on auto master tech in Easton, MA. I could get his thoughts and save you some driving. I bet he has someone in Brockton or somewhere down closer to you.

 

[tpenfield]

If you DO end up working the heads I have business experience with Brittons in Beverly, MA on lots of car engine heads. Never a hiccup. I know Cape Cod is a long way from Cape Ann but they are good.
My nephew is a full on auto master tech in Easton, MA. I could get his thoughts and save you some driving. I bet he has someone in Brockton or somewhere down closer to you.

Yea, I don't actually live on Cape Cod, just have a house there. So, anywhere from Southern NH to RI is reachable. I will check out some of these places that you mentioned. I have used a place in Southboro, MA (J and M) for some head work and they were fine. They also do a fair amount of full rebuilds.

If/when I do the engine work, it will probably be both top and bottom end re-builds.


I am thinking: valve job . . . lower end bearings . . . rings . . . probably need a bit of crankshaft grinding, but hopefully not too much. Not sure how that will compare to the cost of a quality long block, as those 7.4 engines are getting scarce . . . and expensive (I would want new if they could still be had). I'd prefer to rebuild my own engines if all I could get was a rebuilt long block.

Thank you for the referrals, still may be a couple of years off, unless something turns for the worse.

 

[Saline Marina]

It seems strange that the world would ever run out of the 454 engine components for another 20 years or so. Just guessing here but I'll venture probably 10 million are in existence. I got a 454 truck reman longblock engine for around $2500, this was around 4 years ago for a truck 25 years old without a roller in the valvetrain (it does have roller pivot/roller tip chromemoly rockers now). I have beaten the hell out of it towing stuff one should need a diesel for. The nice thing about remans done in a factory setting are they have a repetitive process that's under some sort of control (for example they may have bought an old transfer line from Tonawanda and refurbed it) They offer a 50k mile warranty with it, so that says something about the confidence in their process. I'd choose that every single day of the week over taking parts to various local job shops, not to knock their work, but do they give you a 50k warranty? (I realize we are speaking of marine apps where mileage doesn't exactly apply)

 

[Tail_Gunner]

Update:

I did the 'snake oil' thing on the engines today, just to see if and what sort of difference a little bit of combustion chamber cleaning makes on the numbers.

So, I picked up 4 cans of Seafoam and did the treatment.

Rather than pouring the seafoam into the air intake as typical instructions indicate, I mixed a 50/50 solution of seafoam and regular gasoline totaling 1 quart. Then I hooked my 'mix' to the fuel line and ran it thru the fuel system (MPI) until it had drank most of it.

Then I turned off the engine(s) and disconnected the ignition wire and cranked the engine for several 7-8 second 'blasts', figuring it would basically flood the engine/cylinders.

I let the engine(s) sit for about an hour and then started them back up, now connected to the regular gas/fuel line. I revved the engines up a bit maybe hit 4K a couple of times.

Then I kept the engines rev'ed at about 2500 RPM and induced a slight spray of water into the intakes - this essentially will perform a second 'steam' cleaning of the combustion chambers. So, I gave it about 5 minutes of water, then ran as normal for another 5 minutes or so.

After that was all said and done, I ran another compression test. Hear are the numbers:

Port Engine: Before/After

1= 137/129
3= 129/123
5= 126/122
7= 135/131

2= 140/138
4= 134/126
6= 133/127
8= 140/130

Starboard Engine: Before/After

1= 125/126
3= 124/126
5= 118/122
7= 117/122

2= 124/127
4= 128/125
6= 127/120
8= 128/130

Anyway, it looks like the Starboard engine was a little higher after the combustion chamber cleaning and the port engine was a bit lower. I think I am going to leave things alone for the time being. Maybe give it further consideration for next year.

Well it's not often id wade into this type of conversation but the fact it did move the needle in short a time I shall. So the real snake oil...Dextron 11 ATF and acetone...50/50 mix...pull the plugs...fill the chamber's...Fill the valve cover's full right to the top and let the mixture sit for a few day's. The majority of the fluid will seep into the oil pan you will have to drain the mess.....However you will not have any sticky rings....no sticky valves..The whole system will be a clean as those as the head chamber's when you introduced water in them...And yes you will have to plug the head's so the they wont drain the mixture straight down....Sound's crazy yes about as crazy as cleaning a carb with vinegar but that to works without fail.

https://www.engineeringforchange.org/news/2012/08/14/how_to_make_penetrating_oil.html

:behindsofa:.........I just had to...eace:

 

[alldodge]

It seems strange that the world would ever run out of the 454 engine components for another 20 years or so. Just guessing here but I'll venture probably 10 million are in existence. I got a 454 truck reman longblock engine for around $2500, this was around 4 years ago for a truck 25 years old without a roller in the valvetrain (it does have roller pivot/roller tip chromemoly rockers now). I have beaten the hell out of it towing stuff one should need a diesel for. The nice thing about remans done in a factory setting are they have a repetitive process that's under some sort of control (for example they may have bought an old transfer line from Tonawanda and refurbed it) They offer a 50k mile warranty with it, so that says something about the confidence in their process. I'd choose that every single day of the week over taking parts to various local job shops, not to knock their work, but do they give you a 50k warranty? (I realize we are speaking of marine apps where mileage doesn't exactly apply)

Marine, not marine I have a Merc reman 454 sitting in my shop with less then 200 hours and has a spun bearing. If it is repetitive or not, stuff happens. Unless it's new, remans all deal with the quality of the machinery doing the work and the quality of the person controlling the work. A worn cutter or a machine out of calibration has a large impact on the outcome of the final process

 

[tpenfield]

Well it's not often id wade into this type of conversation but the fact it did move the needle in short a time I shall. So the real snake oil...Dextron 11 ATF and acetone...50/50 mix...pull the plugs...fill the chamber's...Fill the valve cover's full right to the top and let the mixture sit for a few day's. The majority of the fluid will seep into the oil pan you will have to drain the mess.....However you will not have any sticky rings....no sticky valves..The whole system will be a clean as those as the head chamber's when you introduced water in them...And yes you will have to plug the head's so the they wont drain the mixture straight down....Sound's crazy yes about as crazy as cleaning a carb with vinegar but that to works without fail.

https://www.engineeringforchange.org...ating_oil.html

:behindsofa:.........I just had to...eace:

Glad to have you chiming in Tail_Gunner :thumb:

I am thinking that the reduction in compression on the port engine was mostly due to de-carbonization and the increase of compression on the starboard engine was due to valve seat improvements. Anyway . . .

I did have a similar thought to your 'snake oil' approach . . . I was planning on a second seafoam treatment. This time, I would use my compression test adaptor hose and a funnel to 'fill' the combustion chamber with seafoam at TDC of the exhaust stroke on each cylinder, so it will soak into the valves, valve seats, rings, etc. Then purge the cylinders of the liquid, let it sit for a while and run the engine, along with some more water induction to provide an additional cleaning.

Finally, I would run a compression and cylinder leak test and put the engines to bed for the winter. My borescope has shipped, so I could get some internal pics of the engine as well, just to see if I can get to shiny metal.

Anyway, not expecting miracles, but perhaps some longevity, so I can save up the $10K for new engines.

BTW - I was searching some threads on MEFI modules and tuning, and came accross RSBJ's thread on his 4.3 rebuild. You had conversed with him quite a bit, but I noticed he has not posted since completing the engine. Any word about how things turned out?

 

[tpenfield]

Marine, not marine I have a Merc reman 454 sitting in my shop with less then 200 hours and has a spun bearing. If it is repetitive or not, stuff happens. Unless it's new, remans all deal with the quality of the machinery doing the work and the quality of the person controlling the work. A worn cutter or a machine out of calibration has a large impact on the outcome of the final process

Yea, it looks like Bondo was right . . . new 7.4L long blocks are about $5K each. Quality remans are about $3000-3500 w/ a core charge. So, not a huge difference.

I also agree with AllDodge . . . remans are subject to a lot of variables. Quality of shop equipment, skill of the craftsman, and also, the condition of the donor engine. So, lots of variables.

 

[Tail_Gunner]

BTW - I was searching some threads on MEFI modules and tuning, and came accross RSBJ's thread on his 4.3 rebuild. You had conversed with him quite a bit, but I noticed he has not posted since completing the engine. Any word about how things turned out?

It went quite well I never asked but can almost tell you he had a strong backround in aviation mech's. He was dead on with the compression ratio...the piston to wall clearance now I wouild like to know if the engine held up long term. More than probably he was very astute, with his comment on the two stroke tell's me he was quite happy 4.3's really wind up fast and pull hard with a decent cam.