This 1985 merc 470 is the first inboard I have owned. It will run amazing at home on the muffs for 20 minutes or so with out any overheating.But the first time I had it on the lake, it got hot and melted the rubber exhaust boot. I immediatly shut it off and let it cool enough to get me the short distance to shore. Once home I did a compression test to make sure no major damage was done. 115 psi - 130 psi in all 4. But why did it get hot? The radiator fluid is topped off and looks healthy. Is there an Impeller in the drive that pushes water to the motor? Or is there some type of water pump? Can the average back yard mechanic attempt this repair? Any help would be appreiciated. Thank you

Hey guys I have a problem here I am trying to resolve , the choke tube on my 120 is stripped out on the male piece that comes out of the carb. I was on the lake yesterday running wide open when the boat started losing power and increasing and decreasing rpms. I heard a loud whistle and I believe it is coming from the choke inlet on the carb. This piece has been stripped since I got the boat I had it on there the best I could but no where near tight. Do you guys have any suggestions to fix this and also could that sucking air cause the boat to lose power and decrease and increase rpms. I have tried to cut new threads but the male end is worn down to small.

I looked around here and didn't see anything on it so I'm gonna ask. Can I install an electric fuel pump on a 1970 120 mer cruiser. My manual pump has stopped working.

I see a lot of talk and post about buying a new cap and rotor from auto part stores like napa, is this acceptable. I would rather do that then drive the hour to ******** hoping they have what I need. If this works what do I need to ask for since I doubt the clerk knows what a 1996 5.7 l mercruiser is.

My 1997 Sea Ray 190 has a 4.3L GenII with 100 hours total time. Took it out for a run and ran well until I brought it in to the dock and notice the power was diminishing. The engine had the classic coffee cream color spewing out the valve cover breather tubes. I removed the plugs and all were good except number 2 which was full of water. Is the likely cause a head gasket? I've read other posts and the primary response is "cracked block", which scares the heck out of me. But I don't believe that to be the problem as there is no visable leaks and the engine runs great otherwise. If the block is cracked, would it more than likely be noticed if I removed the head and intake manifold? From the diagrams, the water seems to pass through the upper part of the block, and if cracked would seem to cause more severe symptoms. Thanks for your consideration.

1986 Mercruiser 260 5.7

Here is a weird one. Last year before I wrapped my boat I changed the oil and noticed some oil on the back of one of the heads. I figured it to be a bad valve cover gasket so I pulled the valve cover to find out the valve cover was rotted. I hade two small block chevy valve covers so I got new gaskets and swapped them out. That's all I did besides draining the engine of water. Just the oil change, valve cover swap, took batteries out, drained the water and covered it up. No other changes since last year when it was running fine.

This year I have taken the boat out twice and only when in gear and under 1500 RPM's (Trolling through a no wake) I every so often hear a puff of air come from the engine compartment and the engine stumbles for a brief second. Other than that, it runs smooth and strong, no other problems. All tuned up and happy. Idelling (not in gear) fine, motoring over 1500 RPM's fine. Just trolling, every about 1 to 1-1/2 minutes I hear a puff of air and the engine stumbles for a very quick second.

The breather tubes appear hooked up correctly and are obstruction free.

Weird right?

I am wondering if at low RPM crankcase pressure is building up in the valve covers and overcoming the breather tubes and blowing out through the valve cover gasket every once in a while causing the puff sound, I mean I guess a quick drop in crankcase pressure would cause a slight stumble right?

I think I will tighten the valve covers next time I take it out and see if it goes away.

I find it very odd, I thought I would post to see if anyone else ever heard of anything similar???

From what I've read so far it seems that it won't harm my boat motor or outdrive to shift it into forward and reverse while it is idleing on a hose. I just had to rewire my shift assist switch because I installed a new motor and new ignition system. I would like to test it before I put it back in the water but will it operate properly without the water pressure on the prop? Thanks for any input on this. 86 5.7 Mercruiser Alpha one.

Hello Guys.
I have been offered to buy a running mercruiser 140 engine (#2960713)1968 to 1972 for $150. The owner told me that it runs and has not been over bored and the compression is 120/120/120/70.
My own engine is a 1984/5 that has one low cylinder (90). Can I over bore (if necessary) the older block and rebuild my 1984 on this restored block or is it too different?
Thank you for your advice and opinions.
Cornelis.

When I lower the drive on my boat I can hear a creaking noise. I only hear it when on the trailer. Any ideas on if this is normal or not? It's a new boat so maybe things need to be broken in?

Looked at an 84' sea ray with a newer 140 engine. Oil was clear before it started, now it is a milkshake. Water was 1/4" on top of #4 piston. How can we find out if it is a head/ block / gasket problem, or a bad manifold? We need to do this without tearing the engine apart.

It was winterized correctly and there are no external cracks.

Hello everyone and thanks for letting me into your forum. I own a 2008 Bayliner 185 BR. 3.0 litre Merc. I/O Bought new and stored indoors during the winter. (climate controlled). The boat and motor has 57 hours on it. Oil and all other fluids are changed every year. Distributor cap and rotor are Mallory marine grade so as not to deteriorate quickly due to moisture. ignition is electronic. A syphon port was installed on the fuel cell so no fuel is left in the tank during storage. While prepping for another season and running in the driveway, (elephant ears on and water supplied to motor), When I lower the throttle to WOT, the motor bogs almost to the point of dying before beginning to take fuel and rev up where the RPM should be in relation to the Throttle lever position. The boat has an extended warranty but I have had the boat in for warranty work twice in the past and the minor issues were never repaired until I fixed them myself. As I now have absolutely zero faith in a warranty that I paid for, I am turning to the source of information that I should have done in the first place. Distributor timing is set at 2 deg. ATDC which is right where it should be. Fuel filter has not been replaced and I have an electronic fuel pump to replace the stock as merc/GM are notorious for a very poorly designed fuel delivery system. The only adjustments on the carb are idle speed. Mixer screws are capped as the motor is the ultra efficient model. Any and all help would be appreciated and thank you all again for reading.
This is the first (and last) I/O I will ever own. I own a 1998 Tracker 190 with a Johnson 75 O/B. This boat sits outside every winter.( covered). Some years with fuel in tank, some years without. EVERY season I throw in the Batts, Prime the fuel bulb and turn key start. Ignition was upgraded to electronic. Best motor/boat combo I have every owned.

My boat battery discharges while running on the water. Brought it home charged the battery now have no lights in dash, I checked fuses and circit bracker on motor. Had a friend tell me the alt. is bad, Also sparkes when you hook up the battery now. If i hook the charger to it, it trips the breaker in the charger its a 90 5.7 merc.

I have a 2010 Mercruiser 5.0TKS carburated S/N1A603164 with an Alpha S/N 1A240442. The alarm goes off when slowing down from full throttle (WOT 4800+) right at 4000rpms. It is a single beep. It does not go off if cruising at 4000rpms, only when slowing down. All gauges show fine with water temp at 170-180, oil pressure at 40 at idle and 75 at WOT. I did notice when I changed the drive lube I over filled the drive lube bottle. It is about 3/8 inch above the max full line. could that be the issue. Otherwise it seems to run fine. I am out of ideas. I could use the opinions of the experts here at iboats. :confused:

I own a 2006 Tahoe Q4, with 4.3l Mercruiser, carbureted. Sometimes, after a hard run, then sitting around for a while, I go to start the engine & the thing starts, then dies after a few seconds. Each time I start it, it starts right up, then dies. I can keep doing this over & over, but it's the same result...start/die, start/die, start/die... It will just randomly start up one time, and be just fin e. I figure maybe it's cooling, from me having the engine hatch open. Only does this sometimes. Does this sound like it could be vaporlocking?

Not sure what is going on but when I am at a stand still and then drop the throttle i get a pause in the motor almost like it shuts down and then it takes off. One time I even thought that I heard a pop like a back fire. Would that have something to do with the spark plugs? Or What? Thanks for any help! Matt