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Hard Starting 470

D

dlux

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"I took all of last week off a

"I took all of last week off and spent most of it on the water, Fantastic week! Boat ran great with the exception of hard starting after it has ran awhile, I have to wait 15 to 20 min for it to restart, turns over ok, just wont fire. Running at 180 degrees,getting Fuel and spark, I've heard this is common with the 470 but I haven't found a cure. Any thoughts. Thanks"
 
"Sounds like vapor lock.
I do

"Sounds like vapor lock.
I don't know much about 470's, but if its mechanical fuel pump you could try switching it to an electric pump.

Rod"
 
"No it's not, seems like i

"No it's not, seems like it's hot and just needs to cool down a bit to restart,you can try multiple times with no start then bang starts up and purrs, one more strange thing when your'e trying to restart sometimes coolant will boil out of the res. cap, I just had the valves done and replaced the head gasket and when it's running good at Idle there are no bubble coming up thru the resivoir and the oil is clean, where would this pressure be coming from?"
 
"Thanks Rod,It seems to be get

"Thanks Rod,It seems to be getting fuel, you can look down the carb and see it squirt when you throttle it, Is there a Marine grade electrical pump? I would think there would be a diff between auto grade."
 
"When it does start, is it rou

"When it does start, is it rough for a few seconds with perhaps some blackish smoke?
This would indicate a hot flooding condition, which sounds like carb leakage into the manifold.

I am not sure what marine electric pump is used on the 4 bangers, but there is one for the Merc 4.3 V-6, which would do the job nicely. You can get a PN on this site and search it out.

Sounds like it gets quite heat soaked after shutdown. Why are you running at 180 F? What T'stat is installed? Not sure what the 470 is supposed to run, but 160 is normal for most RWC engines. Older engines used 140 T'stats.
The bubbling sounds like the coolant gets quite warm after shutdown.

Rod"
 
"No Black smoke,runs great, I

"No Black smoke,runs great, I had a problem with the floats sticking and after the third time I removed the recently installed needle seat with the old one I took out and haven't had a flooding problem since. The coolant coming out of the res. cap only happens when I'm experiencing this starting problem and I'm turning the engine over. I will check on the T-stat 180/160, could help, Thanks"
 
Merc. parts manual calls for 1

Merc. parts manual calls for 160 deg. for all years. Check the stat. for the correct temp. PNs are 76270T for up thru 1982 and 1983 and on is 99155A1. I believe the latter is an upgrade.

Check the heat exchanger for proper cooling; tubes may be partly clogged. OD impeller may need replacement also.
 
"Thanks, That could be a big p

"Thanks, That could be a big part of my problem, how would I check the exchanger for proper cooling, pull it and check the flow?"
 
Change the T'stat first an

Change the T'stat first and see how it cools. If the temp drops to the 160-170 deg. range then you may not need to do anything.

To service it you remove the one bolted on end and use a long wire brush to remove any scale buildup on the inside of the tubes. Flush it and replace the cover w/a new gasket. Pressurize it to see if it has any pinholes that need attention. If you don't want to mess w/it then take it to a radiator shop.
 
"Pulled my stat last night and

"Pulled my stat last night and it seemd to be stuck in a partial open mode which could explain why it ran at a consistent 180, Is replacing the impeller a tough job on an alpha OD?"
 
"180 F seems pretty hot. Mine

"180 F seems pretty hot. Mine runs at a consistent 140 F. I think with the aluminum block Mercruiser designed this motor to run cooler than most. hard starting I would check the carb. Try and squirt some starting fluid in the carb next time it gets difficult to see if it starts easier, that will give you a clue that it is fuel or carb related."
 
"The merc 4 cyclinder motor CL

"The merc 4 cyclinder motor CLOSED COOLING came with a 160' thermostst. 180' under normal running conditions is normal. or at least it was when I used to work on them!!!!!

My bet is the timing chain is stretched and when it is warm it streches even more and causes hard starting............SEEN IT many times.

To check this, hook up a timing light and watch the timming mark. If it moves erraticly or up and down while the engine is running at a constant rpm then the timing chain is stretched and needs replacement. A good timing chain and the points set properly and the timing set correctly the engine should fire on the first turn when warm."
 
"Thanks, The timing mark is st

"Thanks, The timing mark is stable, I replaced the impeller and T-Stat and also upgraded my Battery Cables to a #2 Gauge cable, it now runs at a cool 170 and starts strong every time ( Knock on wood) Thanks to all for the help, My current challenge is trying to get my shift cables adjusted, another post."
 
"Here ya go on the cables.....

"Here ya go on the cables.........

Whith the boat on a trailer and the KEY OUT OF THE INGNITION!!!!!!!!

1. put the controll into full forward wide open throttle position.

2.Raise outdrive aprox 1/2 the distance under normal trim function (NOT TRAILER) trim ram (stainless shaft exposure) should be aprox 1 1/2 to 2 inches.
3 have second person rotate prop counterclockwise untill solid (no clicking or intermitten engagement) engagement.
4. disconect short shift cable and controll cable from shift bracket.
5. With plastic shift cable end PUSHED all the way in, confirm full forward engagement at the prop.
6. Measure 6 inches ( NO MORE THAN 6) from the center of the eye in the plastic end to the center of the brass trunion. 1/16 of an inch LESS is acceptable (5 15/16").
7 install short cable back into shift bracket.

8 with controll shifter still in full forward full throttle position adjust brass trunion on controll cable to fit onto easily onto shift bracket. The manual says to spin trunion up to four (4) additional turns in one direction but I do not have that info at hand. I do and do not do this so it is up to you.
9. after both cables are in place put control shifter in neutral and have second person spin prop. It should spin freely with no "clicking".
10. Now move the control shift handle to the forward position. ( 10:00 oclock) detent. Move the handle slowly so you can feel this!!! Do not move it any futher than the detent!!

11. Have the person spin the prop counterclockwise and confirm full foward gear engagement. If this is good move to next step.
12. shift back to neutral (12:00 oclock) make sure props spins freely.
13. Shift to reverse slowly, to the 2:00 oclock position detent and NO futher.
14 have the person spin the prop clockwise to confirm full reverse engagement. If not full engagement go to next step.
15. If no engagement or it can be manually popped out of reverse at the prop then you adjust this by loosening the 7/16 hex STUD under the cable end(not the nut on top of the cable) that the end of the short shift cable mounts to. There is a slot that this stud is allowed to move. Adjust the stud in the direction that will PULL the cable end. There is not very much movement but normally it is sufficient. After this adjustment is made put controll in neutral and then back into reverse to the detent (2:00 oclock) position.
If you have good reverse engagement now recheck forward gear again. If you do not have good forward you can adjust the controll cable trunion a small amount to get forward in or try to split the distance you adjusted the short cable STUD in the slot.

As with any used/old system there are gives and takes sometimes needed to get this to work.

Do not adjust the SHORT shift cable after the ~6" demension is set ever again!!!!

All adjustments are done with the controll cable or the slot in the bracket.

If all of this does not work than either the short cable or the controll cable or both have to much SLACK in them.



Hope this helps."
 
"To follow up on the adjustmen

"To follow up on the adjustment in the manual that I was unsure of here it is.

When installing the (control cable) on the shift bracket after the 6 inch adjustment on the (short shift cable)and its intallation,

you spin the brass trunion on the (control cable) 4 turns AWAY from the black plactic cable end."
 
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