3.7 mercruiser mysterious ticking noise

[ericcarr2000]

Ok, I have been trying to track down this mysterious ticking noise for quite some time now. It is only evident from idle to about 1000 RPM's. When you hit the 1000 RPM mark it goes away, at least you cant hear it anyways. You back off the throttle and there it is again. Ive tried to re-torque the valves down to the 24 ft. lb. mark, i've replaced all the lifters with new ones and the thing is still there. Ive had a few people say that a carb running too lean could be the cause, or maybe even timing being a tad bit out of adjustment. I've checked the timing and it is dead on at the 6 degrees BTDC mark. Any suggestions on this one here would be greatly appreciated. Please view the video ive attached,

3.7 mercruiser ticking - YouTube

 

[stonyloam]

Re: 3.7 mercruiser mysterious ticking noise

It could be the same as the last 470 ticking noise we had here. There could be a hole in one of the plugs in the head, and it is exhaust noise. There are two plugs ( about 5/8 inch in diameter), one in front and one in back. Check to see if you can feel exhaust blowing out of either when the engine is running.

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Hi Stony, Yeah I read up on that post and put my finger over them and really couldn't feel any air coming out from there. I just went out and checked that again and still couldn't feel anything...

 

[artificialreef]

Re: 3.7 mercruiser mysterious ticking noise

How about wrestling coaches suggestion with the piece of tissue paper? Maybe your hands are so caloused from working on that motor you have no discernable feeling left in them. Sounds like i am joking but try it.

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Lol, Ill give that a try here in a few hours I guess. What did you do just wrinkle up a piece of paper and cram it in there?

 

[wrestling coach]

Re: 3.7 mercruiser mysterious ticking noise

Lol, Ill give that a try here in a few hours I guess. What did you do just wrinkle up a piece of paper and cram it in there?

The idea is to hang something light like tissue in front of the area to detect air movement you might otherwise not feel.

Dennis

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Hmmm... That might be difficult because my alternator is on top instead of the bottom causing air to probably move the tissue giving a false result..Ill give it a try though.

 

[wrestling coach]

Re: 3.7 mercruiser mysterious ticking noise

Hmmm... That might be difficult because my alternator is on top instead of the bottom causing air to probably move the tissue giving a false result..Ill give it a try though.

I believe you have another one of these casting plugs in the same location on the other end of the head as well. And if it makes you feel any better I have a similar if not identical tick/knock in my '82 470 2bbl.

Dennis

 

[wrestling coach]

Re: 3.7 mercruiser mysterious ticking noise

At the risk of starting an "oil thread" (please don't) what are you running in the engine? If you are running a multi-viscosity I'd suggest switching to a straight 30 weight of choice and see if the problem goes away.

This is not my thread but I think you are on to something with regards to oil.

Dennis

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Hmm.. You know I was thinking of changing the oil before taking her out this year. I usually change it once a year and have yet to as of yet. I did however try to add some of that CD-2 oil treatment to see if that would help, but nope, still ticks. I will try to just change it over to 30 weight oil though. The last time I changed it I used shell Rotella oil.

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Will do. Ill be changing it this weekend most likely.

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Ok, I just got done changing my oil in her, did seem a little thin but to no avail. With new 30 weight oil in her she is still making that ticking noise. I did look at my oil pressure gauge......Shouldn't the oil pressure be at least 40 pounds at idle.......When I started her the oil pressure was just below the 40 pound mark, around 36 or 38 or so. To get her above the 40 pound mark I have to accelerate it and I noticed that when the pressure gauge goes above the 40 mark, that's when the ticking noise goes away. I could have swore that last year the oil pressure was at around the 60 mark at idle. Give me your thoughts on what you guys think...Im thinking I need a new oil pump now......

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

My next question is this. Is there any way I can bypass the internal pump and install an external oil pump so I don't have to pull the motor?......

 

[stonyloam]

Re: 3.7 mercruiser mysterious ticking noise

According to the manual you should be running 40 wt, or 25W-40.

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

So running 10W30 isn't recommended in your opinion then?

 

[stonyloam]

Re: 3.7 mercruiser mysterious ticking noise

Mercruiser recommends either straight 40 Wt (old recommendation) or 25W 40 (new recommendation). It's not my opinion, it's theirs, I am just passing along the information.

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Ok, well I just got done changing the oil again in her to get that CD-2 detergent out of her and changed it to the 25W-40. The oil pressure seemed to be a tad bit higher, but the ticking is there there. Im assuming the reason the oil I took out almost looked like thinned out mud is because of that CD-2 detergent I put in there last week.

 

[natemoore]

Re: 3.7 mercruiser mysterious ticking noise

My 470 registers very little oil pressure at idle, and about 40 at higher rpms when warmed up. The oil pump is brand new OEM. There's a tech supp bulletin regarding the oil pressure. PSI of oil flow isn't as important as volume being pumped.

Did you check the valve lifter clearances when you re-torqued?

 

[ericcarr2000]

Re: 3.7 mercruiser mysterious ticking noise

Im actually awaiting for the arrival of the clearance tool and go-no-go gauge to be able to check them...

My 470 registers very little oil pressure at idle, and about 40 at higher rpms when warmed up. The oil pump is brand new OEM. There's a tech supp bulletin regarding the oil pressure. PSI of oil flow isn't as important as volume being pumped.

Did you check the valve lifter clearances when you re-torqued?

 

[natemoore]

Re: 3.7 mercruiser mysterious ticking noise

I'm cheap. I made a valve lifter compressor out of some scrap metal, and the clearance gauge out of a piece of Corian. I live for reverse-engineering things.