Tachometer Repair

[JimG]

Has anyone had a good experience getting a tach repaired? Would you recommend the shop?

[andyofcolumbusmerkur]

Check with the vendors here about a whole cluster or a parts cluster. But the cluster could be fine and the cable to blame.

[merkurdriver]

Sometimes you can see a really obvious crack in the one soldier joint on the back of the tach once you have the tach out of the cluster. Usually the red wire. Its a 30 second fix once you have the whole thing apart. Anglin has some nice pics detailing it here:
viewtopic.php?t=10805&postdays=0&postorder=asc&start=30

[taylor0987]

Mine was intermittent. I didn't see any bad solder joints, so I just heated up all of them up quickly with the soldering iron. This resolved the issue.

[my8950]

Curious about this....I've tried a few different clusters and my tach still reads about 80% of what it should be, roughly...
The tach moves slow and just doesn't seem "correct"...
I'm wondering if there are any other thoughts on this.
An idea I had was to overlay a new wire directly from the EEC to the input on the back of the cluster and see what that does.

[Ed Lijewski]

A thought.

You/your father now have a Scorpio I think. If that Scorp's tach seems to work okay, try swapping the coil from it into the XR and observe that tach's operation.

YMMV

[my8950]

A thought.

You/your father now have a Scorpio I think. If that Scorp's tach seems to work okay, try swapping the coil from it into the XR and observe that tach's operation.

YMMV

Ed, do you think think the V6 coil might make up for the 1/3 difference in the tach reading? Since the V6 has two more cylinders, it might make the 4 cylinder read higher?

[Ed Lijewski]

Yup.

YMMV

[my8950]

Yup.

YMMV

[Ed Lijewski]

It's worth testing as the tach signal feeds out from one side of the two coil harness prongs, and as you've reflowed the gauge solder joints.

YMMV

[merkurdriver]

The coils are identical between both cars.

[merkurdriver]

A thought.

You/your father now have a Scorpio I think. If that Scorp's tach seems to work okay, try swapping the coil from it into the XR and observe that tach's operation.

YMMV

Ed, do you think think the V6 coil might make up for the 1/3 difference in the tach reading? Since the V6 has two more cylinders, it might make the 4 cylinder read higher?

The coil is the exact same part between the XR4Ti and the Scorpio. There is no difference between the V6 coil and the 4 cyl coil.

Worth swapping just to rule out the coil, but there is no way a "Scorpio coil" is going to make an XR tach read higher. ( As long as that XR has a 100% good coil in it ).

The cylinder number calibration is in the tach itself.

[Ed Lijewski]

Noah's post responding to mine, and my response to his, were sarcasm, Mike...

I know the coils are identical, hence the thought to swap to rule out the tach signal feed side of coil for my8950 as involved in his poor functioning tach. Yes, it's a remote possibility, but my8950 has been trying to get his tach working for some time (see MCA Facebook posts) after following all other recommendations for fixing it. The tach signal received by the tach has to be at spec for the tach to read rpms correctly. Someone may know how to assess that signal directly, but in the absence of anyone offering that info, trying the coil swap is a proxy for that.

BTW Mike, on MCA facebook yesterday there was a post with comments by a member who couldn't figure out how to mount and hang your Merkur Depot SS exhaust system, so he seemed unlikely to buy it although he was seriously considering it. You could answer his questions satisfactorily; no one else could.

YMMV

[John Brennan]

BTW Mike, on MCA facebook yesterday there was a post with comments by a member who couldn't figure out how to mount and hang your Merkur Depot SS exhaust system, so he seemed unlikely to buy it although he was seriously considering it. You could answer his questions satisfactorily; no one else could.

YMMV

Thank you, Ed-- see new post, Merkur Depot Exhaust Fitment for the follow-up:

http://forums.merkurclub.net/forum/view ... 30&t=34508

[dan_xr4]

I did the Tachometer red wire repair on my XR4Ti today. So far the tachometer is working great.

I used a soldering iron on the circuit board, behind where the red wire attaches. I heated the solder until it melted and then let it solidify. The solder joint did not look bad, but it did look slightly different from the solder joints around it. I did this for only the red wire. My tachometer is now alive after more than 20 years of not working.

The instructions and links by Chris Anglin were helpful even without the pictures, approximately here:

viewtopic.php?t=10805&postdays=0&postorder=asc&start=30

The post by Ryan which was linked is also good:

viewtopic.php?t=10560