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merc 350 engine noise help

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danthemancarolina

Contributing Member
Had a noise in my 350 mercruiser. i took the engine out and did what the manual described to fix. my camshaft is fine, lifter were fine, rods fine,piston rods fine. I took the block to a machine shop to polish (it originally got water in it from the exhaust manifold-replaced now). replace all of the rod bearings. replace the main camshaft bearing. (non looked slipped but thats what the book said).

now, it will start and idle fine. but when i add a little rpm, i get the same darn ticking noise. well its more of a really loud tapping noise. i really dont thnk that its valve lash since it was making the same sound prior to rebuild. I did not have the heads redone, maybe a valve is stuck, or maybe one of the lifters have sunk? geez this is really ticking me off...
 
danthemancarolina said:
i dont know if it has a mechanical fuel pump or not. is that what you are asking?
Click to expand...

Ayuh,... You just rebuilt the motor,..??
Yet don't know whether it's got a mechanical fuel pump,..??

That alone makes me question the Quality of work done on the Rebuild.....

Did you MEASSURE All the hard parts, before reassembley,..??
How many thousandths are the bearing clearances,..?? Mains,..?? Rods,..?? Cam,..??
 
bondo said:
Ayuh,... You just rebuilt the motor,..??
Yet don't know whether it's got a mechanical fuel pump,..??

That alone makes me question the Quality of work done on the Rebuild.....

Did you MEASSURE All the hard parts, before reassembley,..??
How many thousandths are the bearing clearances,..?? Mains,..?? Rods,..?? Cam,..??
Click to expand...

I measured eveything. they were all within factory specs. had the camshaft measured at the shop that did my polishing and all lobes were fine. The motor was a merc reman, but I couldnt afford the risers at that time. (learned the hard way). so basically it has not been run but 1 time since the engine swap. I am not a mechanic, but i do understand the manual. also have engine rebuild dvd that are fantastic. thats why I changed bearings based on what the book said. I also had the block polished since it had water in it. I had a mechanic come listen, he thought it was spark advance. so I changed the unit in the rotor cap. he set timming and checked wiring. So I know its not that. I thought this is a help site,
 
OK Cheif, i put the vacuum directly on the pump output. started the engine and it went between 8-9psi. movement with the idle of the engine. I also put some oil additive and took to the lake and puttered around. at about 3k rpm is the ungodly popping sound. when i tried to increase rpm, it just backfired something fierce and lost power. What should I check next? thanks Dan
chiefalen said:
Do a vacuum test:

How to Use and Interpret a Vacuum Gauge

On Fire vacuum gage

All mechanical fuel pumps make noise.

I replied to your e-mail.
Click to expand...
 
oh, i also had my daughter drive while at 3k rpm. i used my wifes stethoscope. It really sounded the loudest at cyclinder #3. I also listened to the pump and no adverse noise there.
 
You probably burned/broke the intake valve to cylinder #3
Check compression on cylinders.... start on the odd numbered side.
 
yes a tuliped lifter would do it. Got sucked in. But i don't understand, your pump is giving you 8-9 psi pressure?

And what number did the guage give you when you hooked it to a vacuum port.

Go to the link how to interpret a vacuum gauge when running the motor you watch the gauge, what did it do and what scene on the link was closest to it.

Popping ,backfiring, timing is fugazied, for some reason.

Timing messed up will show with the vacuum test. So will the valves or guides.

Will also tell if you have a serious leak.

Lets start over.

1- Verify that all the spark plug wires are going to the correct, plug. Just don't say they are verify each one.

2- All is well under the dist cap. You have wobble in the shaft ? Zero no wobble is acceptable.

3- Rotor good. What you have points i don't know if you have points. Weights good move freely.

All checked post back.

I think if all the above is good, you should do a copression test and write down each cylinder and the number.

Do it on a warm motor all the plugs out and throttle fully down.

Read the plugs.

Spark Plugs
 
" I did not have the heads redone, maybe a valve is stuck, or maybe one of the lifters have sunk? geez this is really ticking me off... "

Big booboo...listen to chiefalen and sandkicker.
 
well finally found time today to work on boat. Chief, I have not redone the fuel pump test because the guage I have didnt fit exactly perfect on the thread. So, friend has one coming today at cost. My plan is to replace since its the original! I also ordered lifters. I borrowed a compression tester and here are the numbers.
1. 149
3. 150
5. 148
7 150
2,4,6,8 were all 150
 
danthemancarolina
I may get fried for this statement, but putting new lifters on an old cam is not the best way to go. The different wear patterns can cause problems on the hardened surfaces. I personally would look elsewhere for the problem, as lifter noise is pretty distinct and a decent mechanic would pick up on it. Go with chiefalen, vacuum readings will give you a wealth of information.
Bert
 
bertg said:
danthemancarolina
I may get fried for this statement, but putting new lifters on an old cam is not the best way to go. The different wear patterns can cause problems on the hardened surfaces. I personally would look elsewhere for the problem, as lifter noise is pretty distinct and a decent mechanic would pick up on it. Go with chiefalen, vacuum readings will give you a wealth of information.
Bert
Click to expand...
Hi Bert, Well the cam itself probably has no more than 8 hours run time on it. so I am hoping that wont be a problem. My new fuel pump will be here this afternoon. I will put it in tonight and start her up and see if the noise is gone. I will post my results later.
 
jeez i don't know y you spent money on the fuel pump ? can you cancel it?

Anyway compression numbers can't be better, one or 2 pounds off is nothing.

Vacuum test?

You already have the gauge i posted the links tell me what the result is.
 
chiefalen said:
jeez don't spend any money yet please.
Click to expand...
:eek: LOL thanks Alen, Listen I got the parts less than cost. If it is in fact the fuel pump. I will be able to send the lifters back. I have just waited sooo long to fix this that I want to be done. My pump should be here around 6pm eastern time. It did have rust in it, so I am replacing anyway. when I put the new pump, I will tell you the results before proceding with the lifters.

A friend that owns a service shop, said IF I had water in the motor, probabaly the oil pump is screwed. I hope he is not right because I dont want to yank the motor out again! Since you all are so good about posting, I will make sure to wait after the fuel pump deal...thanks a whole bunch!!!! Dan ;)
 
you stole the parts hah.

Ok i just don't like to spend one nickle that i don't have to, your happy then i'm happy.

Good luck with all your endeavors.
 
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oh about the oil pump after you run it the oil looks clean ? Not milky.

After about 3 times changing the oil and filter the milky part will go away and the oil pump should not be damaged.

Sorry for not responding to your entire question. Kids here running all over , making a racket g-d i love the house with the kids here so quiet when they are out.
 
chiefalen said:
oh about the oil pump after you run it the oil looks clean ? Not milky.

After about 3 times changing the oil and filter the milky part will go away and the oil pump should not be damaged.

Sorry for not responding to your entire question. Kids here running all over , making a racket g-d i love the house with the kids here so quiet when they are out.
Click to expand...
LOL about the kids, been there done that......
 
9pm eastern time. got the new pump installed, primed her and started up. let warm up for a while sounds good. rev up to 2500rpm no sound. then i went quickly to about 3500 and it starts making the very loud tapping noise that sounds like its coming from the carb......:eek:...... I immediately throttle down and shut motor off. waiting for my gurus to tell me what next....thanks :cool:
 
"...sounds good. rev up to 2500rpm no sound. then i went quickly to about 3500 and it starts making the very loud tapping noise that sounds like its coming from the carb......:eek:....."

RPMs over 1500 are a big NO NO if the engine is run on a garden hose or in neutral on the water. Marine engines should be running under load over 1500 RPMs!
 
Ok here is an update. took it to my friends shop this am. 2 master mechanics confirmed it was the lifters. did a vaacuum test which confirmed. (thanks alan). time now is 1.26 eastern time. I have the new lifters soaking in oil and have removed the old ones. Getting ready to cleanup the old gaskets. It,s hot as F&*$%k here. Think I may have to have a beer while the lifters soak. P.s. If you read by 2:30, will an hour soak for the new lifters be long enough? thanks Dan
 
yes a hour is more then enough, leave the beer alone . Hah i do the same thing to get away from my wifey for lifey. F--king hot here too.

Just curious what did the vacuum gauge do ?
 
Hey Alan, well the new pump leaks so ordered another one. Now, I set my valve lash per the manual. I turned the balancer to top dead center. I instaled the distrubutor with the top thingy pointed toward the number one cyclinder. lined up the top with the thingy and put the top back on. So I start the engine and it wont idle. I have to give it alot of gas to get it started. It is making a very awful backfiring sound (when its running). I tried to advance the distributor but doesnt help. what may I be doing wrong? I had my son help make sure that the spark wires were in the right sequence. I then checked again yesterday just to be sure.....hmmmmm help... p.s. I have the valve covers off so i can double check the lash. AI have cardboard around so the oil doesnt splash everywhere...
 
Did you use a timing light to set the timing? Are the carb mixture screws set at 1.25 turns out from fully inward?
 
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