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Mercruiser AAlpha Leg No trim down

T

tailor

New member
"Hi,

I have twin 4.3L mercr

"Hi,

I have twin 4.3L mercruisers. One is in the trailer position, and I can't get it down.

So far I've replaced both solenoids, cleaned all the contacts, checked there is power to the busbar. Last check was to remove the blue/white wire from the up solenoid and hit the trim switch. According to Clymer if the trim motor runs, then it's a wiring harness problem. I got no motor run, so presume the problem is not in the harness. I don't think the limit switch is adjusted incorrectly since it's been OK to now, and hasn't been touched.

Also I have twin controls, and neither set works, which I guess rules out a faulty switch.

At this point I'm lost, so any advice would be welcome, thanks."
 
"What happens when you jump th

"What happens when you jump the top studs on the down solenoid?

<center><table border=1><tr><td>http://www.marineengine.com/discus/icons/attachment_icon.gif""" align=left alt=""application/vnd.openxmlformats-officedocument.wordprocessingml.document"">how the trim works
[url=""][b]How the trim.docx[/b][/url] (12.6 k)</td></tr></table></center>"
 
"Guy

Jumping power to the p

"Guy

Jumping power to the positive stud runs the pump motor.

Bondo,

Thanks for the link. I did purchase at great expense the correct manuals for both motor and leg, but have put them somewhere so safe I can't find them just now. Grrr."
 
"Have been working too many ho

"Have been working too many hours to get back to my boat until just now.

Jumping power to the down solenoid dropped the leg right down as I expectd it would, even without anyone standing on the leg, however I still have no activity from the toggle switch or trailer switch from either station.

It would seem to be something simple if I could find my service manuals, or could actually access the link from Bondo, but without either I'm at a loss."
 
"READ and follow the direction

"READ and follow the directions in the "How the trim works" that I sent you. Open the cover to your bridge control and look, pull and tug on the red, black and red w/purple stripe wires. Based on your comments that neither station works, I would assume you have lost a ground circuit or 12 volt circuit common to both.

There is an in-line 20 amp fuse on a red wire in a black barrell at the trim assy. Some switch control assys. also have a 20 amp fuse at the 3 button type control switch. The barrell fuse can look good but actually be defective; the end cap glue dries out and the connection is broken; BTDT. That barrell fuse is the power source of the switches.

Remove the small 3 wire plug w/a clamp on it at the trim pump assy; they are notorious for vibrating loose. Inspect, clean if needed and reinstall tightly and test the switches. If they work, reinstall the clamp and recheck that the switches still work. Clamping it wrong can break the plug's contacts. The red w/purple stripe wire on the male side of the plug is the power to the trim switches."
 
"I have to say I'm impress

"I have to say I'm impressed by the depth of knowledge by you folks.

I have a problem with getting my outdrive to go down ...goes up just fine. I replaced the entire pump/motor/resevoir unit.The new pump does the same thing. In reading the manual (thanks to Bondo), I was surprised to find that the pressure relief valve on the "up" side was 2,200 psi. The "down" side is only 600 PSI. I've decided that the cylinders are tight (boat has been sitting a very long time)and the pump will move them on the high pressure (up) side but the lower pressure side just blows the oil past the pressure relief valve. I've swapped the hoses in order to get the outdrive up & down. The cylinders do move and I thought would free up with use. Do I dare adjust the 600lb pressure relieve valve up till it will move the cylinder ...or just swap in the higher (2,200) pressure relieve valve?"
 
"[b]"The cylinders do move

""The cylinders do move and I thought would free up with use."

Ayuh,... Fix it by rebuilding the cylinders,...
Not Micky Mousing it..."
 
"I've had this same proble

"I've had this same problem since the motor was a year or so old if the boat sat a few weeks at a time- though it would tend to work it's way out with a few minutes of movement back & forth. I had previously thought I was working air out of the system I didn't suspect the pressure relief valve/tight cylinder. Odd, no evidence of water in the old oil - though the screens on the pick-ups were disintegrated. Lots of tiny bits of mesh sunk to the bottom of the resevoir.

Having worked with heavy equipment it wasn't that unusual for cylinders (& more) to be a bit stiff if something sat around long enough. It would tend to loosen up with a little use. I do subscribe to the priciple of fixing something right but already have over $2000 into parts trying to get the boat rehabed. New exhaust manifolds & risers, new cables, new shifter, batteries & much more. Funds have dried up. This seems to be the last "issue". 1974 Seacraft, repowered in 97, only 220 hours on it - almost none in the last few years. The boat really needs some use.

Curious ...why wouldn't the PSI be the same on both sides? "Down" always seemed weak."
 
"Going "down" is aided

"Going "down" is aided by the pressure of the prop going foward, going "up" needs to overcome this downward pressure to raise the drive in trim mode."
 
DON'T touch the valve body

DON'T touch the valve body or it will never be right again. Flush out the heavy oil fluid with ATF and see if it will move.
 
"Work keeps getting in the way

"Work keeps getting in the way, but I've finally got to do some testing.

Continuity of wires to trim limit switch, and Blue and Green from the three wire connector at the pump assembly seem to be OK. All fuses check out alright, and I have power where it should be on the pump assembly.

Continuity on the trim switch is OK, however the trailer switch doesn't show continuity when depressed.

Apart from that, my batteries need charging but show 11.6 volts at the terminal blocks, but the red wire from the three wire connector only shows about 8.4 volts. Probably a silly question, but would the fact I have dual station controls have a bearing on this.?? Or is it just due to the nlow charge in the batteries.?

Could save me from a cramped difficult place if that were the case since the second station is not easily accessable.

I also disconnected the trim switch assembly and connected a switch directly between the red and green, then the red and blue from the three wire connector. Nothing happened, even though I did have the leg in the partly down position. (down enough to test the trim limit switch continuity.

Other than changing the trailer switch I'm somewhat out of ideas, apart from the voltage drop."
 
""DON'T touch the valv

""DON'T touch the valve body or it will never be right again. Flush out the heavy oil fluid with ATF and see if it will move."

Good suggestion to maybe get the unit moving back & forth ...but alas, too late.

I took the pressure releif valves off of the old unit and confirmed there was no magic here, just a spring and ball. The high pressure valve used a much heavier spring - thus the 2,200 PSI. That confirmed that a turn or two on the low pressure valve wouldn't boost the psi dramatically. In fact there wasn't a huge amount of adjustment left for the valve body.I took three clockwise turns on the valve, then backed it off one full turn to make sure I wasn't bottoming out the spring then locked it back down with the backing nut. I reinstalled and "presto", we're back in action. Apparently the pressure required was only slightly more than the valve originally wanted to allow. After cycling it several times to eliminate air, it was apparent that the outdrive was already moving much more freely (I had also greased all fittings up front & it could be that the tightness wasn't all in the pistons but where the outdrive pivots).

Interesting note: Thinking I would purge the air from the pump before hooking up my lines, I found that it would NOT pick up a prime - just spit some oil and mostly air until I finally attached the trim hoses. It then immediately started pumping oil.

Thanks for the suggestions ...and again for the repair manual. I'll let you know if anything blows apart sometime down the road.}"
 
"John:

"Other than chan

"John:

"Other than changing the trailer switch I'm somewhat out of ideas, apart from the voltage drop."

Did you use a jumper at the switch? Also; did you check connectors for corrosion? A fully charged battery will make a difference. But, the 3.2 volt drop spells a dirty or corroded connection; follow the voltage drop until it goes up."
 
"Hi Guy,

Yes, I did jump th

"Hi Guy,

Yes, I did jump the switch terminals, without success, but for some reason I didn't think to use a different positive power source. As soon as I jumped the wires from the power lead of the other leg, I got results.

At least the problem has been isolated to the red wire from the three connector plug near the pump. And since the internal red connector of that plug is showing 11.6 volts the fault must lie in the one red wire to the switch conections. A continuity check seems to prove this and I'm surprised to get any voltage through, but being spasmodic my guess is a fractured cable.

Guess I will have to replace that section of harness, or try to. With 4 metres under the floor I can only hope the builders didn't tape the harness to anything else under the floor or I'm in a lot of pain.

Thank you very much for your assistance, and especially for the explanation of how the power cricuits work. Invaluable information


John"
 
"John:

I replaced the whole

"John:

I replaced the whole harness but you can replace just the red wire. On the trim control end, do you have a black plastic coupler w/4 wires in/out both ends? If you do, open it up and you'll see a fractured red wire."
 
"Guy,

I cant find any coupl

"Guy,

I cant find any coupler on the harness and I can only see about 2 ft before it enters the floor. It looks to me like a standard Mercruiser 20ft harness. If the worst comes to the worst I can run a seperate red wire, provided the break isnt in the three wire connector at the pump end, which the way my luck is running, is a possibility.

My wife wants to spend a couple of days at Moreton Island over Easter, so I need to get this fixed>


If all else fails I could do a temporary fix with an inline fused bridge from the red wire of the other control, but am not excited at that idea.



John"
 
"Guy,

Just a short message

"Guy,

Just a short message to thank you for your help.

I finally found the problem which was in the wiring harness. There were a number of places where all the wires appeared to have been crushed, which eventually resulted in complete severance of the red wire. I'm not sure if they were crushed as I was able to pull them without a lot of effort, which could mean the wires were continually banging on something and that caused the damage. Guess I'll never know unless the starboard harness start to exhibit the same symptons.

I've fitted a new harness and all seems well.

John"
 
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