3b water temperature gauge issues (1 Viewer)

[nhs15]

Stock 3b engine in a 1989 BJ70 nonturbo. Engine runs great, been driving regularly for past two weeks.
Water temperature gauge stays at bottom at all times. Whats a good place to start - the sending unit?
Thanks

 

[Squash]

Check the wiring.
Or grab an off the shelf unit and test the sender.
Installed a real time unit mounted to Lhd left dash pad to monitor on big hills in order to drive according to engine temps.

 

[nhs15]

During a coolant flush, both sensors and a bad thermostat was replaced. The gauge does move now but during normal like driving to work, outside temps in the 60-70s, less than 10 miles, it only goes up a few mm above low. During a long road trip, fully loaded with 3 people and gear, for 3 hours plus it moved about 1/3 the way up. Not sure what the norm is

 

[Reinhardtius]

During a coolant flush, both sensors and a bad thermostat was replaced. The gauge does move now but during normal like driving to work, outside temps in the 60-70s, less than 10 miles, it only goes up a few mm above low. During a long road trip, fully loaded with 3 people and gear, for 3 hours plus it moved about 1/3 the way up. Not sure what the norm is

Not normal compared to my experience with my 3b. It hovers around 40% when cruising down the highway or town.

 

[nhs15]

I was having some engine work done by my local mechanic and it looks like he replaced the bad thermostat with a napa part without telling me. Would this part work or should I get a 3b specific one from cruiser outfitters?

https://www.napaonline.com/en/p/MRD233

 

[Reinhardtius]

I was having some engine work done by my local mechanic and it looks like he replaced the bad thermostat with a napa part without telling me. Would this part work or should I get a 3b specific one from cruiser outfitters?

https://www.napaonline.com/en/p/MRD233

I can't personally say whether it will work, but probably works fine. You can go to the Toyota parts counter and get an OE thermostat, but it may not do anything different for you. To me, it sounds like an electrical issue.

I could posit that your issue has something to do with resistance, perhaps in the wiring, or likely in the gauge cluster, which is dampening the signal on the water temp gauge. Others will tell you that the OE water temp gauge is more a guide than accurate. You may consider installing an Auber instruments water temp gauge to confirm normal operating temperatures, and track back your electrical issue, should there be one.

 

[dcruiser666]

It certainly wouldn't hurt to install a better gauge, the Toyota gauge is kind of binary. However, the thermostat you posted does look like the incorrect one that is often used in 70s by mistake. Using the correct thermostat is critical for getting a proper reading due to the location of the sender. The correct thermostat is designed to block the lower outlet in the housing when it opens, this maintains coolant contact with the sender and regulates flow. I think you’re getting a bad reading and improper cooling.

 

[dcruiser666]

This is what's listed for your year and model. Both genuine parts are available from partsouq.com for less than $20 total.

 

[nhs15]

Thanks. I'll switch to OEM. I just ordered one.

 

[nhs15]

You were right. Swapped for an oem thermostate, and then did a super flush, and now I have a temp gauge that works and super hot air in the cabin. Didn't get the rubber o-ring gasket, just the housing gasket, so there is some wiggle room in there around perimeter of thermostat. Not sure if its 100% necessary. I'll put an order in for one next time I'm ordering parts from CO.

The napa thermostat was more cylinder shaped so maybe it blocked the sensors, who knows.

 

[dcruiser666]

Good news. I’m not 100% on the o-ring being required. It’s a weird one, there is clearly a provision for it and the part exists but it’s not displayed on the parts diagram. I have never heard definitively that it is required and it’s omission from the diagram is a mistake by Toyota. Seems like everything’s fine without it though.

 

[nhs15]

Yeah its wierd. The napa one that I took out had one and it was super snug in there. But parts diagram for the oem one definitely doesnt have it.