Speedometer reads way too fast

[bigcountry78]

Thank you blackwater for that in depth response. I've driven the truck for about 150 miles now, trying to get all the readings for it to pass inspection. It hasn't been on the road since 2015. The tach reads correctly. The gas gauge and oil pressure gauge aren't 100% accurate, temp only goes up to 150 or so. Alternator guage seems accurate. Called a couple local wrecking yards and no one has a truck this old.

 

[east302]

Try car-part.com for local salvage yard inventories. eBay is another (more expensive) alternative.

I want to say that the clusters were specific to V6/V8...maybe the tach had a different redline.


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[kennythewelder]

Were there big tires on the truck before ? It sounds like the calibration is off. The only way to know for sure, is to have a programmer hooked up , and see what is what. You can try a transmission shop, they recal the ECM for your tires. If nothing else, then that will eliminate this as an issue.

 

[Blackwater]

Thank you blackwater for that in depth response. I've driven the truck for about 150 miles now, trying to get all the readings for it to pass inspection. It hasn't been on the road since 2015. The tach reads correctly. The gas gauge and oil pressure gauge aren't 100% accurate, temp only goes up to 150 or so. Alternator guage seems accurate. Called a couple local wrecking yards and no one has a truck this old.

Now I have the same problem with my temp gage as well. Just the temp. I changed both sensors and the instrument cluster and no change with the old clusters. I have a Dakota Digital one waiting on me to return along with a couple of other items. I am changing the dash out. There is a difference in the cluster connections on the different years. my truck is a version 3 while the dashes that I pulled from the recking yards are a version 1 and 2.

 

[bigcountry78]

I finally got this fixed I think. My dad found a cluster from a v6 truck, it said 95 model on the rear of the cluster. I wasn’t sure it would work but I swapped it anyway and everything including the speedo seems to work properly now. Odometer has the wrong mileage now and the gauges are faded more compared to my old cluster but I’m just happy it worked. Temp still sits at 150-160, but my heat works great so I don’t know what’s up with that. My 98 with a 350 always ran dead on 210 so this is new, but I’ve heard several others say that their trucks run at 160 as well. As far as tire size goes, it’s only had 265-75-16 on it for the last 12 years.

 

[Blackwater]

these engines are recommended to run at 190 degrees but I have no issues with a 160 to 180 degree thermostat. just as long as you don't reach 212 then you have a problem.

 

[bigcountry78]

Im thinking about replacing the thermostat and seeing if I can get it to run a little hotter. But then again it’s doing fine as is, maybe I should leave it alone lol.

 

[df2x4]

Im thinking about replacing the thermostat and seeing if I can get it to run a little hotter. But then again it’s doing fine as is, maybe I should leave it alone lol.

Almost sounds like your thermostat might be stuck open. It's a cheap part, might be worth a shot. ACDelco 131-151 is the factory 195 degree thermostat.

https://www.amazon.com/ACDelco-131-151-Original-Equipment-Thermostat/dp/B000EQRH5G

Alternatively if you want to test the one you have, you could take it out and verify that it's closed, then drop it in a pot of boiling water and see if it opens up.

 

[bigcountry78]

Just out of curiosity though, if it was stuck open would the heat still work properly? The thing has a great heater in it even running at 160.

 

[Blackwater]

If you have heat and it’s not overheating the I would just leave it alone. Mine doing the same after I replaced the thermostat.


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