Oh this can't be good. MErcruiser 5.0L loud clicking.

[MajBach]

Hi again, everyone. Here are the deets:

2002 Maxum with 5.0L Mercruiser with approx 500 hours. Hasn't been run in 2 years but was stored properly. I had some problems with heavy water contamination earlier this year in my home fuel supply so I checked my fuel tank in the boat prior to starting and it was fine.

It took the typical a lot of cranking over before it started. I cranked it 10 seconds a couple of times, then paused, then gave the throttle a couple of pumps and left it open by about 50%. When I tried the third time, it coughed once or twice then backfired. Or made a sound similar but not the same as a backfire. I stopped, took a look around, remarked to myself "it's never backfired before", then resumed trying. This time it fired but not enough to keep running on its own without continuing to crank over. I saw small amounts of blue smoke - as it does every year. Then it ran on it's own, albeit with the clicking sound.
The sound it worrisome - not like any I have ever heard and it's loud even at idle. It is definitely tied to engine rpm but not completely consistent in volume such being it may be really faint or even skip a click every 10th revolution or so. The volume of the sound increases exceptionally with rpm and even a little goose on the throttle sounds like the thing will explode.

The only thing that comes to mind as I write this is to wonder can too much oil in the crankcase cause this. I had a little over half of a 9.5 litre jug of oil that I dumped into it. I can't recall what the oil capacity is on the engine but I figured it's at least 5 litres.
Any idea on what I should do next (after I check the oil)? Below is a link to 2 sound clips in two different audio formats to listen to.
Thanks

https://drive.google.com/drive/folde...eB?usp=sharing

**UPDATE**

After writing the above I went and checked the oil - fine. I then started it again. Started fine but the clicking noise took 10 seconds before it returned. The engine died - I restarted and it ran fine for a few seconds then died again. Restarted and it ran fine continuously but with the clicking. I looked deeper to see if I could locate the sound. The carb! Most definitely in the carb. The chamber was acting like some resonator ( I had the flame arrester off). When I placed my hand over the carb, the noise was very muffled. When I put the arrester on, also very muffled albeit very much noticeable.
This is perplexing. How can this be related to rpm but inside the carb? There is some type of electrical unit on the side of the carb. What does it do?

 

[Bt Doctur]

stuck valve, broken /cracked rocker arm , bent pushrod

 

[MajBach]

stuck valve, broken /cracked rocker arm , bent pushrod

Uck. That doesn't sound good. If it's a stuck valve, could that cause back pressure into the carb? I can't even imagine the process to repair any of those things.

 

[Bt Doctur]

If an intake is stuck open , Yes. Pull the manifolds and pull the valve covers

 

[tank1949]

Uck. That doesn't sound good. If it's a stuck valve, could that cause back pressure into the carb? I can't even imagine the process to repair any of those things.

You should have used a distributor oil priming tool before starting up a motor that set for two years. I suspect now, if you had motor running, oil galleys, etc should be primed. Pray! Maybe... You may want to use one anyway to ensure oil has pumped up lifters. After priming, spin over motor (w/o) coil connected and plugs out. Watch for rocker arms not functioning. If ok, do compression test with RELIABLE tester. I had one with bad Schrader valve.. A can of mystery oil might free up lifter. Be patient.

 

[MajBach]

I don't even know what a distributor priming tool is.

 

[kenny nunez]

Actually it is most likely a exhaust valve causing the back pressure since it is not opening. The best way to store a engine is to fog it through the carburetor with so much light oil while opening the throttle that it kills all the bugs in the neighborhood and almost summons the Fire department. After that if you can fill the carburetor float chamber with Marvel Mystery oil through the vent tube it will keep the remaining gas from turning to varnish and also keep the accelerator pump from drying up.

 

[MajBach]

Well, the time has come to make an informed decision. Unfortunately, I don’t yet feel I am informed as much as I should be. A lot of what I am stating is not just a practical “…do I fix, replace or sell it?” It’s about getting older, lifestyle changes, and letting go of things dear to me. I appreciate anyone who takes the time to read the following, give it some serious consideration and lend me some sound advice.

I went back out again to the boat and it started flawlessly. It ran for a good 30 seconds without making a sound before the clicking started. There was a noticeable change from smooth idle to a slightly rough idle when the sound returned. I’m going to take a semi-educated guess that this means it IS NOT a broken or bent something and most likely a sticky valve.

I’m an Officer on a Coast Guard vessel which means I am on the water every day or on vacation and I am single with no dependants or debt. I have a single car garage that I split my time maintaining 3 motorcycles, 2 boats and a couple of SUVs. Tough life, I know and I am not complaining about how hard I have it. The problem in front of me is deciding on whether to fix this boat or let it go. It needs new risers (as they are factory – but I have been watching the temps closely every year. I had them inspected when I bought the boat at 170 hours), and new U-joints. I do all of the work on all of my toys and haven’t been to a shop in 20 years. Most of that success has been due to people and places like this forum. But I have kind of reached the point where I have had enough of fixing and maintaining crap. After I started the boat a few minutes ago I took a good look in the engine. No way can I do the risers myself. I’ve been promising myself I would them for several winters past but just haven’t found the time. But now I am glad I never even tried. I’m 6’4” and over 300 lbs and just reaching the oil filter takes me over an hour. I’ve never even checked the plugs on the boat so the idea of doing a pressure test or leak-down test? Nada. Not anymore.

However, I’ve done a little more research on stuck valves and watched some videos. Someone here even said “Pray”, “Mircale Oil” and “…brass hammer”. The valve covers do seem pretty easy to access and I would probably go so far as to attempt removing them if I thought there was a slight chance that by doing so I could remedy my issue.

So here are some of the considerations I have in determining what I want to do with this beast that has brought me so much joy:

• risers need to be done, no getting around it.
• Probably needs a good tune up too since all I have done is change filters, keep the oil clean and high quality, and spray fogging oil into it each winter
• Even if I do free up a stuck valve, it’s almost certainly going to return, or is it?
• Will I need a valve job? If so, these can be done when the risers are done and probably save me some labor
• The U-joints I can probably do myself but what the hell if I am going to take it into the shop,
• What is this boat worth, realistically if I disclose all the current issues I have with it?
• Is repowering it a realistic or practical option?

Truth is, over the past couple of years I’ve been slowly looking to upgrade this boat but prices seem so high compared to when I bought it when the recession hit in 2009. Even though I’d like a bigger boat, I don’t want to let this one go for free since it’s probably worth more to me than I could expect to sell it for, but realistically, I don’t know what someone would pay for it.

What are new risers going to cost all-in?
What is a valve job going to cost?
A rebuilt engine?
A new engine?

Which decision makes the most sense? I really don’t know and I need help finding these answers. I know it’s like asking “How long is a piece of string?” but this is where I am at.

First of all….how likely is it I can determine the extent of the current repair by lifting the valve covers? What do I look for and what do I do if I find a stuck valve? Can the engine be run with the valve covers off so I can watch what is happening?

Thanks so much for all of your time.

R

 

[nola mike]

Worst case is a head rebuild and replace... But we don't know what your problem is. Boats are expensive, much more so if you're not doing the labor. Buying another boat won't save you time unless it's brand new, and will never save you money. Getting ahead of yourself with talk about a new engine. This could also be timing, carb issue, etc. If you don't feel like dealing with it the only way to make an informed decision is to pay someone to do the grunt work and figure it out. But you already knew that, right?

 

[Searay205]

Strange you haven't been to a shop in 20 years but are struggling with this issue. You must own Honda's. Sale the boat and move on. You haven't used in a couple of years its time to pass it on. Boat sales have skyrocketed, you may get a great price. At minimum i would find a qualified marine mechanic with references to put his eyes on it, if he can get it going the sale price just went up. Either way unload it.

 

[Searay205]

By the way i had lifters tick on cars for 50K miles. annoying but never created a problem. 2002 maxium with 5.0 carb I assume probably $4K-$7K depending on condition

 

[MajBach]

Hi again everyone. Nothing new to report really; haven't had a lot of time to work on the boat. I did pull off one valve cover and quickly realized I don't even know what I am looking for so I put it back together. I'm certain one way or another I will be taking this to a mechanic and then probably selling the boat.
I'm writing to today hoping someone will take a few moments to help me understand the mechanics of what is happening inside the engine...I just want to better know. I look at the forums threads and realize I only come here when I have a problem I need help fixing and I imagine most of the posters here are in the same boat - haha. But, I don't choose to do my own mechanical work to save money, I do it mostly I want to know what is broken, why and how to prevent it.
I drained the oil and replaced it with new stuff and a quart of Mystery Oil or whatever the red stuff is called. I let the engine run up to operating temp and will let it sit a few days now. I am not hopeful for a positive outcome and even if the problem does go away, it still needs to be seen by a mechanic. But something I did notice about the oil which was brand new a week ago is that it came out looking like chocolate milk. Not quite like it was mixed with water but definitely muddy and dirty looking. And that's with ony running at idle a few minutes. That has to be tell tale of something. I am expecting most will think water accumulated in the engine as it sat and caused things to corrode and mixed in with the new oil. Alright, lesosn learned on that front anyway.
Regarding the popping noise through the carb though; I am really curious as to whats going on. I scoured the internet trying to find a video of someone with the same problem to see if its the same as what I am experiencing but came up emty.
So to reiterate, the boat starts okay but has a loud popping noise emanating from the carb. It is directly tied to engine rpm and gets louder as well as rpm goes up. There is also definitely at least one cylinder missing - for whatever reason - as even though it runs 'smooth', something isn't right. The popping noise can be muffled by placing my hand over the open carb but, there is no back pressure or flame even though the popping noise sounds like some kind of a air pressure disturbance. In my mind, I am thinking if this is a stuck valve or one that isn't seating all the way, it MUST be the intake valve. How else would the pressure wave be coming through the carb? BTW, there is no visible sign of the throttle valve moving with each popping noise. Like I said, it's just a noise.
So, going forward with the stuck valve intake valve theory, this would mean air and gas is being drawn into a cylinder like normal then the valve doesn't close up properly and on the compression stroke, the air gas is being forced back out the way it came. Then there is a spark. Wouldn't that ignite the mixture and lead to a back fire? Even if the gas wasn't igniting, should the force of the piston forcing the mixture back through the carb at least be accompanied by some puff of air or visible fuel?
I am really curious as to what is happening internally and would appreciate anyone taking the time to paint me the picute. Thanks.

 

[tank1949]

Hi again everyone. Nothing new to report really; haven't had a lot of time to work on the boat. I did pull off one valve cover and quickly realized I don't even know what I am looking for so I put it back together. I'm certain one way or another I will be taking this to a mechanic and then probably selling the boat.
I'm writing to today hoping someone will take a few moments to help me understand the mechanics of what is happening inside the engine...I just want to better know. I look at the forums threads and realize I only come here when I have a problem I need help fixing and I imagine most of the posters here are in the same boat - haha. But, I don't choose to do my own mechanical work to save money, I do it mostly I want to know what is broken, why and how to prevent it.
I drained the oil and replaced it with new stuff and a quart of Mystery Oil or whatever the red stuff is called. I let the engine run up to operating temp and will let it sit a few days now. I am not hopeful for a positive outcome and even if the problem does go away, it still needs to be seen by a mechanic. But something I did notice about the oil which was brand new a week ago is that it came out looking like chocolate milk. Not quite like it was mixed with water but definitely muddy and dirty looking. And that's with ony running at idle a few minutes. That has to be tell tale of something. I am expecting most will think water accumulated in the engine as it sat and caused things to corrode and mixed in with the new oil. Alright, lesosn learned on that front anyway.
Regarding the popping noise through the carb though; I am really curious as to whats going on. I scoured the internet trying to find a video of someone with the same problem to see if its the same as what I am experiencing but came up emty.
So to reiterate, the boat starts okay but has a loud popping noise emanating from the carb. It is directly tied to engine rpm and gets louder as well as rpm goes up. There is also definitely at least one cylinder missing - for whatever reason - as even though it runs 'smooth', something isn't right. The popping noise can be muffled by placing my hand over the open carb but, there is no back pressure or flame even though the popping noise sounds like some kind of a air pressure disturbance. In my mind, I am thinking if this is a stuck valve or one that isn't seating all the way, it MUST be the intake valve. How else would the pressure wave be coming through the carb? BTW, there is no visible sign of the throttle valve moving with each popping noise. Like I said, it's just a noise.
So, going forward with the stuck valve intake valve theory, this would mean air and gas is being drawn into a cylinder like normal then the valve doesn't close up properly and on the compression stroke, the air gas is being forced back out the way it came. Then there is a spark. Wouldn't that ignite the mixture and lead to a back fire? Even if the gas wasn't igniting, should the force of the piston forcing the mixture back through the carb at least be accompanied by some puff of air or visible fuel?
I am really curious as to what is happening internally and would appreciate anyone taking the time to paint me the picute. Thanks.

It is a Chevy V8. If you have a favorite car mechanic, call them up and see if you can take it by them to examine. They will most likely be cheaper and not have the backlog as marinas now have. Good luck!

 

[Jcris]

I agree with tank1949,
You have to get this checked out by a decent mechanic. Ask around, surely someone will be able to point you to good guy with enough experience.

 

[MajBach]

Hi everyone. Thought I would give a final update on this since I made such a big deal of it and in case someone else has the same issues.
I took the boat in to a mechanic and they discovered two cylinders that didn't pass the leakdown test. He figured it was a couple of valves and advised me that it was time to pull the engine and send the upper end out for rebuild but to be ready for surprises once the valves were off. If it was just a bad valve or two, worst case scenarios was $3000 for the repair.
There was a surprise.
Can't recall if he said it was a manifold or a riser (not even sure if I know the difference) but one was bad; bad enough to have let water into all the cylinders. There was rust in all the cylinders and scoring which meant honing the cylinders out. This certainly explains how the brand new oil I put in there came out looking like mud after only 10 minutes of running. On the other habd, I'm surprised it started and ran as smooth as it did, especially with no apparent oil burning.

He stated the cost to rebuild the engine would be near the same as replacing it with a 5.7 he had there that had just been rebuilt.
So two of the options he gave was a 5.7 long block fuel injection which would require all the accessories from my engine (alternator, power steeering etc.) and that he could also attach my closed cooling system from my engine as well. This would cost about $5500 (Canadian dollars) for the engine proper and about $5500 for labour and everything else.
The other option was a 350MPI new from Merc. This engine would be complete (except fore the closed cooling). It would run $15,000 for the engine and parts/labour would bring the total to around $20,000.


Yea, a little steep from what I initially expected.
I had the boat/trailer for sale most of the summer just to see what interest it would generate. I had full disclosure about the known (at the time) issue and had it listed for $23,000 (this included a really beat up but reliable Ford Explorer with a 7500lb tow package) . I had observed one other boat the same as mine that was listed and sold for $30,000. Same year but with the 5.7 litre compared to my 5.0 liter and with more hours. I actually had a few offers for just under $20,000 which I am kind of wishing I had taken. On the other hand, I would have felt pretty crappy if I sold the boat suspecting it was a bad valve or two and instead needed a new engine.

I haven't decided which option I will take; probably the cheaper of the two. Although, I would like to know the difference between the 5.7liter long block to the 350 MPI.
I'll probably keep the boat but may sell it considering how used boats are at an all time high. With a brand new engine and Covid still around another year, I should be able to get $30,000 for it which would mean I break just slightly short of even.

Anyway, thanks for all your input.

 

[Scott Danforth]

a brandy new 5.7 longblock GM motor from GM is only $3200. add a new set of manifolds, some gaskets and do the job yourself and your into it for $4500

local machine shop (not your marine guy) could probably rebuild your 5.0 GM motor for about $1500

heck, even if you had to buy new heads from GM, they are only $900 a pair.

new 6.2 from mercruiser should be about $11,800

 

[MajBach]

The quote he gave me for $11,000 included new manifolds and risers . I've considered the shopping around option for a better price but these guys are the highest rated within an hour radius of where I live and it's not like I can just go collect the boat and engine and take it somewhere else easily. I'll get some more details later but I don't have the time or knowledge to find another mechanic. Don't forget, parts are like double the price here in Canuckistan. I did go into a place a few weeks ago that sells engines from Merc and a 350 MPI was $12,000 from them.
These guys have been pretty good to me so far. But thanks for the input.

 

[Lou C]

when I started reading your story my mind was going to....stuck valves...elbows not replaced....milky oil....its the old story of what happens due to lack of maintenance. I still think it can be done for less than that price. But you have to use who's available in your area I guess. Its worth fixing only if you are going to maintain it though because in 4-5 years you will be back to the same place. Time to replace elbows...etc....
On my old engine in salt water over 18 years its now on its 4th exhaust system!

 

[Rick Stephens]

On choosing whether taking a low ball price - as a buyer there is no excuse to pay a price for a boat with a motor problem of any kind that doesn't include the full discount to replace said motor. I would have offered a lot less than 20K US for a boat that the motor ran crappy, had milky oil and a tick. Selling a boat is often a nightmare. All too often, buying a boat is a worse nightmare.

 

[tank1949]

Hi again, everyone. Here are the deets:

2002 Maxum with 5.0L Mercruiser with approx 500 hours. Hasn't been run in 2 years but was stored properly. I had some problems with heavy water contamination earlier this year in my home fuel supply so I checked my fuel tank in the boat prior to starting and it was fine.

It took the typical a lot of cranking over before it started. I cranked it 10 seconds a couple of times, then paused, then gave the throttle a couple of pumps and left it open by about 50%. When I tried the third time, it coughed once or twice then backfired. Or made a sound similar but not the same as a backfire. I stopped, took a look around, remarked to myself "it's never backfired before", then resumed trying. This time it fired but not enough to keep running on its own without continuing to crank over. I saw small amounts of blue smoke - as it does every year. Then it ran on it's own, albeit with the clicking sound.
The sound it worrisome - not like any I have ever heard and it's loud even at idle. It is definitely tied to engine rpm but not completely consistent in volume such being it may be really faint or even skip a click every 10th revolution or so. The volume of the sound increases exceptionally with rpm and even a little goose on the throttle sounds like the thing will explode.

The only thing that comes to mind as I write this is to wonder can too much oil in the crankcase cause this. I had a little over half of a 9.5 litre jug of oil that I dumped into it. I can't recall what the oil capacity is on the engine but I figured it's at least 5 litres.
Any idea on what I should do next (after I check the oil)? Below is a link to 2 sound clips in two different audio formats to listen to.
Thanks

https://drive.google.com/drive/folde...eB?usp=sharing

**UPDATE**

After writing the above I went and checked the oil - fine. I then started it again. Started fine but the clicking noise took 10 seconds before it returned. The engine died - I restarted and it ran fine for a few seconds then died again. Restarted and it ran fine continuously but with the clicking. I looked deeper to see if I could locate the sound. The carb! Most definitely in the carb. The chamber was acting like some resonator ( I had the flame arrester off). When I placed my hand over the carb, the noise was very muffled. When I put the arrester on, also very muffled albeit very much noticeable.
This is perplexing. How can this be related to rpm but inside the carb? There is some type of electrical unit on the side of the carb. What does it do?

Water over damn now, but in the future it is best to circulate oil via special tool inserted into distributor hole (I can't remember name of it) . It is turned using drill and circulates oil. Carb may be gumed up. Before tearing down, make sure it is getting plenty of gas from fuel tanks. Mud daubers also plug up fuel tank vents so make sure fuel tanks can breath. Plug wire may have came lose and causing clicking sound or exhaust manifold bolt broke and you have an exhaust leak that sounds like a clicking sound. You may have to cycle all the fuel in tank to clean out crap and water.