Logo
FULL SITE MENU

Speedo not working on 4.3 mercruiser

B

boat_user_99

New member
Hi Everyone,

My speedometer on my 2003 Mercruiser 4.3 is not working. I have a Grew 2003 bowrider.

The speedometer intake is at the leading edge of the outdrive - i.e. it's not the type of speedometer where you have a seperate 'finger' at the rear of the hull.

I have the following:

1. Replaced old Faria Guage with New Faria Guage.
2. Blew air in the tube at the front of the outdrive and felt the air coming out at the end of the tube that goes into the back of the speedometer
3. Blew air into the intake port (i.e. up) and blew air down where the tube is connected to the outdrive.
4. Used a drill bit - with my hand - to manually try to clear the intake port.

So far, no luck.

I'm not sure what else I can do - please, can anyone give me some suggestions?

Thanks,
 
sandkicker said:
Blow air in hose on dash board end.... does it come out the drive?
Click to expand...


So I tried to blow air from the tube near the speedo and felt air at the tube by the outdrive. So, it looks like the tube is ok.

I also tried to manually blow air from the tube at the transom to see if it moved the speedo at all - but it didn't - my feeling is that not enough air was going in the tube to move the speedo.

So, I think the blockage/problem is in the lower unit -

Would it be bad if I ran the boat with the tube that connects to the outdrive un-done - My feeling is that water can flow through and maybe dislodge something - my only worry is will that damage the tube or the fitting.
 
boat_user_99 said:
I also tried to manually blow air from the tube at the transom to see if it moved the speedo at all - but it didn't - my feeling is that not enough air was going in the tube to move the speedo.

So, I think the blockage/problem is in the lower unit -

.
Click to expand...

If blowing air into the tube away from the lower unit and towards the speedo AFTER the lower unit did not move the speedo, why would you think the problem is in the lower unit?
 
sandkicker said:
If blowing air into the tube away from the lower unit and towards the speedo AFTER the lower unit did not move the speedo, why would you think the problem is in the lower unit?
Click to expand...

I guess my thinking is that If air can be felt if blowing from either side of the tube, then the tube is ok - as well, and I guess I should have posted this in my original question, I've never seen any water come out of the tube when I disconnect it from the back of the speedometer. I've also not seen water leaking in the boat from the tube - (if there was a leak in the tube not near the speedo, I would think it should be noticeable.

I will try the compressor blowing from the top of the lower unit toward the intake -
 
fastjeff said:
If there's a blockage somewhere, this MIGHT clear it.

Jeff
Click to expand...

So I tried compresses air from the top of the lower unit, but it didn't clear it - I thought I felt air coming out of holes in the side in the lower unit. I also blew (myself) in the intake hole, but no air would go in - so, it looks like something is wedged in their good.


My next attempt is to use something like weed trimmer line and feed it through the port at the top of the lower unit - maybe I can break up whatever is blocking it.
 
So, I was just wondering, what is the tube on the inside of the lower unit made out of? Is it a rubbery/vinyl hose like what runs to the back of the speedometer? Or is something more durable (metal, hard plastic). I guess I want to know how much force I can apply to whatever I jam down there to try to dislodge whatever is in there.
 
Considering the amount of time and money you've spent horsing with this thing, you probably could have bought and installed a GPS speedo, that would tell you how fast you're actually going, as well as a myriad of other info. Just my two cents. . .
 
brian_mcwhirter said:
Considering the amount of time and money you've spent horsing with this thing, you probably could have bought and installed a GPS speedo, that would tell you how fast you're actually going, as well as a myriad of other info. Just my two cents. . .
Click to expand...


Actually, I do have an external Speedo Needle - and Tube - (it came with my new gauges). But id' rather fix the existing speedo system before I start drilling more holes in my hull. Don't want to pay for GPS.

Does anyone know what the intake of the speedo in the lower unit is made of? I want to know how hard to drill (i'm at that point now). Also, if i do drill and make a hole where it shouldn't be, clearly more water will be in the lower unit - is this really bad?
 
I believe it's a bunch of drilled passages in the aluminum housing. Usually there's a 'grill' on each side of the housing that comes off (two bolts).

Jeff
 
kghost said:
It is a stainless steel tube that goes up from the intake hole to the quick connector.
Click to expand...


So, I did get the speedo working - tried manually spinning a drill bit in the intake hole - that didn't do the trick - so, i put that drill bit in a drill and did some gentle drilling - some metal filings came out - and presto - speedo is working again -

I had just replaced all the guages on my boat, and speedo was the only one not working - now everything works (nice to see when i'm on the water)

Thanks for everyone's suggestions and advice.

happy boating to everyone.:)
 
Back
Top