Mercruiser Setting Timing on 3.0L

[DanOnTheBoat]

So Im trying to set my timing on my 2008 mercruiser 3.0L TKS, EST ignition system. My current idle is at 1000RPMS thats where it runs still shakey but it runs and keeps running. If I lower it down to under 1000RPMS like to 800 or 900 RPM it starts to shake and run inconsistantly. Im not sure what the issue is, im assuming timing? So i want to time it but is it okay if i time it at what its idling at right now? At about 1000RPMS?

 

[ESGWheel]

Looks like you have two threads for same topic, so let’s use this one. While this may be a timing issue, can we back up a bit please?

First off, engine serial no. if available.
Second, what is the background on this? Ie is this a new to you boat and its been like this since you got it? Or is a new condition and last season it ran perfectly? Also, what maintenance has been done to it just prior to this issue (if you know)?

The key here is to provide as much info and the good folks here will help guide to the solution.

Thanks.

 

[DanOnTheBoat]

Thanks for getting back!

Serial of engine is; 1A022456

I honestly just bought the boat a few days ago, so its completely new to me... I asked the previous owners about it, elderly couple, they told me it was used at a cottage all its life, but was maintained properly every year.

When I was viewing the boat I did start it up to make sure it runs fine, no milky oil, no ticking, etc. It did have a rough time starting maybe wasnt started in a while, very shakey too.

Maintenance history I have no clue...

Thank you for your help.

 

[ESGWheel]

Thanks for the additional info. Let’s start with some of the basics and I will assume you have the needed tools / knowledge but if not do not be shy to ask, this forum is not about pride, its about helping you get out on the water
My suggestions to get this moving:

• Start with a compression test, best if warm but ok cold. Post results.
• Take pictures of each one of the spark plugs (the business end) and post.
• This looks to have a mechanical fuel pump, and I am usure if there is an inline fuel filter that looks like an oil filter, if yes, unscrew it and dump the contents into a glass jar and let it settle out. Should be crystal clear and no separation (looking for water, bad gas, like that). If no filter, remove hose fm carb and fill a glass container by cranking the engine. CAUTION: disable the ign system > unplug the coil from the wiring harness, you do not what any spark going nor the motor to start during this process.

And there is a whole host of maintenance items to do that include raw water pump impeller, pulling the drive and inspecting the bellows, etc. Others with experience on these sterndrives will hopefully chime in and outline what needs to be done (I am a VP guy with zero experience in the Mercruiser sterndrives).

Also are you new to boating? If yes, suggest read this two threads link and link.

 

[DanOnTheBoat]

Thanks for the help! Definetely will ask with all my questions here lol.

I just checked compression. I hope you can see the pictures. For some reason I wasnt able to get a reading for cylinder 2 and 3... I refuse to believe this because the engine runs. Maybe it was because I used a cheap amazon compression kit? Maybe there was a leak somewhere int eh hose? I also have a borescope and I put that down the spark plug holes for each cylinder, and everything looks like its from factory. There isnt any carbon buildup or anything like that. I can also still see the cross or X lines from the machine on the cylinder walls. I didnt see anything suspicious or anything on there. So yeah Im just confused and worried at the same time...

When I did the compression test I unplugged the center wire fromt he distributor so I wouldnt get spark. I couldnt do anything with the fuel since its mechanical fuel pump.

But anyways for the cylinders Ive cleaned them the other day when I ran the boat, and I ran the engine for a little afterwards. (Cylinder #1 spark plug is at top)

 

[DanOnTheBoat]

Here it is running and idleing in neutral... To me it seems like its running good, althought could be better. If it didnt have compression in 2 out of 4 cylinders there is no way it would run like that...

 

[ESGWheel]

Well sorry to say but you need to believe the data. What comes to mind is a blown head gasket between cly 2 and 3. I assume u tried it more than once, if not do it again. And its ZERO?

Assuming confirmed, its not that big of a deal as long as nothing else bad (like a cracked head).

Do you have an air compressor? If so, can do a poor man’s leak down test to get another data point and confirm head gasket. If not, head is coming off.

Again, fear not, it’s actually fun and think of all the sea stories you get to tell folks when you have fixed the engine all by yourself (note if you have kids of the appropriate age, I encourage you to get them involved and help out > what a great bonding experience!)

For the plugs, looks like its running rich, but we’ll address that later.

For the fuel pump when doing the comp. test > no issue. The fuel pump is always trying to push fuel to the carb when cranking or running and the carb (with its float and needle / seat) shut off the flow. Its akin to your toilet tank > it fills and goes off, no need to close the valve. But good call on unplugging the dist. coil wire > make sure its unplugged from the dist. end and grounded out (and will not come loose). Else can unplug the connector to the coil, up to you.

 

[Scott06]

Thanks for the help! Definetely will ask with all my questions here lol.

I just checked compression. I hope you can see the pictures. For some reason I wasnt able to get a reading for cylinder 2 and 3... I refuse to believe this because the engine runs. Maybe it was because I used a cheap amazon compression kit? Maybe there was a leak somewhere int eh hose? I also have a borescope and I put that down the spark plug holes for each cylinder, and everything looks like its from factory. There isnt any carbon buildup or anything like that. I can also still see the cross or X lines from the machine on the cylinder walls. I didnt see anything suspicious or anything on there. So yeah Im just confused and worried at the same time...

When I did the compression test I unplugged the center wire fromt he distributor so I wouldnt get spark. I couldnt do anything with the fuel since its mechanical fuel pump.

But anyways for the cylinders Ive cleaned them the other day when I ran the boat, and I ran the engine for a little afterwards. (Cylinder #1 spark plug is at top)

if you have zero compression in two adjacent cylinders that would normally point to a blown head gasket between them.

yes unplug center wire on dist , throttle wide open, engine warmed up. Fuel pump doesn't matter as once the bowl is full the float/ needle and seat will close off fuel supply

 

[ESGWheel]

Just watched the video and while i get its a 4 cylinder (meaning a naturally rough running engine vs. others) it frankly sounds like @#$% and is shaking all over the place > like cylinders 2 and 3 are not contributing. Did you take it for a test drive? Under load this motor will not perform at all. Idling is easy.

 

[ESGWheel]

On the plus side, it’s a clean looking boat and will be a lot of fun once all set. We can guide you thru the rebuild needed and (depending) will not be that expensive.

 

[alldodge]

Timing is set at 2* ATDC (yes after not before)

This is the procedure but use 2 ATDC instead of what the procedure shows

Try removing one spark plug at a time while idling and see if each plug causes the same amount of miss. Also recheck your firing order

 

[DanOnTheBoat]

Well sorry to say but you need to believe the data. What comes to mind is a blown head gasket between cly 2 and 3. I assume u tried it more than once, if not do it again. And its ZERO?

Assuming confirmed, its not that big of a deal as long as nothing else bad (like a cracked head).

Do you have an air compressor? If so, can do a poor man’s leak down test to get another data point and confirm head gasket. If not, head is coming off.

Again, fear not, it’s actually fun and think of all the sea stories you get to tell folks when you have fixed the engine all by yourself (note if you have kids of the appropriate age, I encourage you to get them involved and help out > what a great bonding experience!)

For the plugs, looks like its running rich, but we’ll address that later.

For the fuel pump when doing the comp. test > no issue. The fuel pump is always trying to push fuel to the carb when cranking or running and the carb (with its float and needle / seat) shut off the flow. Its akin to your toilet tank > it fills and goes off, no need to close the valve. But good call on unplugging the dist. coil wire > make sure its unplugged from the dist. end and grounded out (and will not come loose). Else can unplug the connector to the coil, up to you.

Ah great... just what I needed to know...

Im no engine mechanic myself. I know theres youtube but I've never in my life worked IN an engine...

Well future kids lol, Im only 20 and this is my second boat never thought id get lucky with a blown headgasket...

Ive never taken the boat on the water either since I did jist get it a few days ago so yeah.

I used to have a 1987 Mercruiser 2.5L and it idle and ran sort of the same and it had really good compression. 165-175 across all cylinders.

Have you guys ever swapped a head gasket before? How much would it cost?

 

[DanOnTheBoat]

On the plus side, it’s a clean looking boat and will be a lot of fun once all set. We can guide you thru the rebuild needed and (depending) will not be that expensive.

Thanks its a nice boat i think I got a good deal for it. It looks clean and well taken care of. Its a 2008 Bayliner 175BR and got it for a little over $2500CAD

 

[ESGWheel]

You got a great deal, congrats!

Prior to pulling anything apart, AD had a great idea of checking the proper firing order and then from there, start it up at that 1000 RPM ‘idle’ and pull (one at a time and then put back) each spark plug wire from the plug. Pull it off completely not just a little bit as the plug could still fire. What you are expecting (hoping for) is that for each plug the RPM should drop the same amount. Giving your compression test results, I would start with nos. 2 and 3 and then go to 1 and 4 as I expect it will stall when pulling 1 and 4.

Yes, I have done head gaskets. Cost could be a little as a new gasket, i.e. nothing else is wrong and put on a new for $30. If the head is cracked due to a possible overheat (which also blew the head gasket), well, then a lot more.
My suggestions:

• Confirm firing order (FO)
• Do the pull the plug off test
• If FO is good and the pull off test shows 2 and 3 not pulling their weight (no significant drop in RPM) then:
  • Do some research about how to pull head as well as for parts > this will get you into the mindset.
  • Evaluate what tools you have / will need. Note I consider any new project a great excuse to buy tools! We can help advise on tools as well, but again trying to get you into the mindset.
  • Determine what sort of budget you are willing to apply to this. Recall you also still must do maintenance to the drive, so that will be some $.
• Post the results of the FO and pull of test and we’ll keep going. Its easy, you can do it so fear not!

Well future kids lol, Im only 20....

Ah, to be young again… I had my first boat when I was 19 and living in Stockholm, Sweeden in the 70s where there was a ratio of 1 boat for every 2 people, or so I was told and it sure seemed like it. It was a blast!

 

[DanOnTheBoat]

You got a great deal, congrats!

Prior to pulling anything apart, AD had a great idea of checking the proper firing order and then from there, start it up at that 1000 RPM ‘idle’ and pull (one at a time and then put back) each spark plug wire from the plug. Pull it off completely not just a little bit as the plug could still fire. What you are expecting (hoping for) is that for each plug the RPM should drop the same amount. Giving your compression test results, I would start with nos. 2 and 3 and then go to 1 and 4 as I expect it will stall when pulling 1 and 4.

Yes, I have done head gaskets. Cost could be a little as a new gasket, i.e. nothing else is wrong and put on a new for $30. If the head is cracked due to a possible overheat (which also blew the head gasket), well, then a lot more.
My suggestions:

• Confirm firing order (FO)
• Do the pull the plug off test
• If FO is good and the pull off test shows 2 and 3 not pulling their weight (no significant drop in RPM) then:
  • Do some research about how to pull head as well as for parts > this will get you into the mindset.
  • Evaluate what tools you have / will need. Note I consider any new project a great excuse to buy tools! We can help advise on tools as well, but again trying to get you into the mindset.
  • Determine what sort of budget you are willing to apply to this. Recall you also still must do maintenance to the drive, so that will be some $.
• Post the results of the FO and pull of test and we’ll keep going. Its easy, you can do it so fear not!

Ah, to be young again… I had my first boat when I was 19 and living in Stockholm, Sweeden in the 70s where there was a ratio of 1 boat for every 2 people, or so I was told and it sure seemed like it. It was a blast!

Thanks I hope i got a good deal lol. Boat overall is in really good shape no tears or anything like that.

Thanks for all the advice and info! Ill try that out, I think that'll be a clearer sign. Is it okay to start and run the engine with a blown headgasket? Im assuming for a short period of time?

If you remember what engine did you do a headgasket on? Im assuming it took a few days to do it? And how much did it cost you? And by any chance if you remember what kind of tools did you end up using? If you remember.

Is there headgasket kits that everybody uses that is trusted and tested? I know if I cheap out on a gasket kit and buy the cheapest one things might take a turn.

 

[ESGWheel]

Please pardon my LOL… I am delighted about your enthusiasm! It's refreshing.

No issue running the motor, you have already been doing it, and a blown head gasket will not cause additional harm for such a short period of time (if continue to run it, say 10s of hrs, then can create problems), so go ahead. Note: have the plug wires installed but not fully, ie make sure they are making a connection but not put on all the way to make it easier to pull off. If when u start it up not running the same, you have a plug wire too far off…

I have done a bunch of head gaskets (I am former but short lived auto mechanic but still do my own work). Others on this forum I am sure have done many many more…

So how much? See post no. 14.

For tools, will need a 3/8 drive socket set along with a ½ drive and a the needed sockets that fit the head bolts along with 2 torque wrenches > one that goes to say 150 Ft-Lbs (1/2 drive but could be 3/8) the other only up to say 20, would be an inch lbs wrench (ie a 240 in lbs) and more then likely it will be a ¼ drive so get a ¼ to 3/8 drive adapter to use the 3/8 sockets, and a ½ to 3/8 adaptor for same reason.

Do you have a Harbor Freight Tool or equivalent where you live? Cheap tools but a low price and good enough for now…

For the head gasket you need to use a Maine one, search around on this forum for what folks prefer.

 

[nola mike]

never done a 3.0, but even as a novice it won't take you a full day. likely most of the people on here giving advice have done a bunch of head gaskets (we're old). in general you want a good quality auto gasket. marine just means not carbon steel. composite or SS should be fine. very cursory check comes up with this.

Amazon.com: FEL-PRO 17200 Engine Cylinder Head Gasket Set : Automotive

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a.co

before you jump on the head gasket though, try to pinpoint the leak. you can buy an actual leak down tester for cheap, or use a compressor and your compression tester to pressurize the bad cylinders and see where you're leaking. zero means a stuck/broken valve or hole in a piston. those are less likely with 2 adjacent cylinders affected though.

 

[DanOnTheBoat]

Thanks! I think I'm overthinking this... I want to try it out because if I don't I'll never learn...

Okay I'll order myself a pressure tester and post my results on here.

 

[DanOnTheBoat]

Please pardon my LOL… I am delighted about your enthusiasm! It's refreshing.

No issue running the motor, you have already been doing it, and a blown head gasket will not cause additional harm for such a short period of time (if continue to run it, say 10s of hrs, then can create problems), so go ahead. Note: have the plug wires installed but not fully, ie make sure they are making a connection but not put on all the way to make it easier to pull off. If when u start it up not running the same, you have a plug wire too far off…

I have done a bunch of head gaskets (I am former but short lived auto mechanic but still do my own work). Others on this forum I am sure have done many many more…

So how much? See post no. 14.

For tools, will need a 3/8 drive socket set along with a ½ drive and a the needed sockets that fit the head bolts along with 2 torque wrenches > one that goes to say 150 Ft-Lbs (1/2 drive but could be 3/8) the other only up to say 20, would be an inch lbs wrench (ie a 240 in lbs) and more then likely it will be a ¼ drive so get a ¼ to 3/8 drive adapter to use the 3/8 sockets, and a ½ to 3/8 adaptor for same reason.

Do you have a Harbor Freight Tool or equivalent where you live? Cheap tools but a low price and good enough for now…

For the head gasket you need to use a Maine one, search around on this forum for what folks prefer.

Thank you I appreciate all the info!

Really under $50? See I don't mind paying lets say $100 for a head gasket kit aslong as its higher quality and I'd have the peace of mind on the water. What kind of engines did you do headgaskets on? Im assuming 3.0 as well? Just curious lol.

I will dig more into this, I should have all those little sockets and adaptors if the bolts that they use on these engines are just the normal six point bolts.

Unfortunately theres not Harbor Freight since I'm up in Toronto, ONT but there is alternatives like it.

 

[Scott Danforth]

Unfortunately theres not Harbor Freight since I'm up in Toronto, ONT but there is alternatives like it.

you have princess auto...... LOL

However at a minimum for tools, get good ones. life is too short to buy cheap tools, because they break