77 K10 LS Swap

[Madhorn]

Ok. The factory 1977 coolant temp sensor for gauges reads 623 ohms setting on my work bench. 40 degrees outside today. The 3 pin 1998 camaro sensor reads 2.6k ohms. Hmmm. Just for fun I went to Autozone and had them pull coolant sensor for an 80 C10 and it was not only a different sensor than the 77 it read higher resistance similar to the 98 sensor. So it seems sometime around 80 the resistance values in the coolant sensors changed.

 

[Camar068]

good troubleshooting

 

[Madhorn]

Forgot to mention that the gauge does appear to be ok. Grounding the sensor wire maxes out the gauge. At the moment I am either considering somehow using the 77 sensor or seeing if it is possible to make the 3 wire work with my gauge. That brings up the question of what is different between early and late model trucks? It’s is the gauge or wireing?

 

[Madhorn]

ICTBillet 551149. I think this the quick easy solution. Will mount in passenger side head.

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[hatzie]

1977 used the 01513321 nailhead temp sensor. This sensor is obsolete and most of the alternatives, including the AC Delco replacement part, only look the same they don't have the same thermal resistance curve as the original Nailhead Sensor.

I believe it was changed in 1979 and again around 1984 to 87 and at least once more before the RV series squares ended production.

You can do one of two things. Get a Letric Limited Nailhead sensor with the correct thermistor curve or get a mid 80's squarebody temp gauge.

 

[Madhorn]

Thanks. That is great info. I noticed that LMC carries 3 different temp gauges. 73-75. 76-79 1st design. 79-87 2nd design. I originally thought the only difference was the face. With what Hatzie mentioned the difference between the 1st and 2nd design should be the resistance curve.

 

[Madhorn]

The adapter showed up today. Would not fit in passenger side head do to clearance with firewall. So it was mounted in water pump where the mini sensor was. So far so good. Did not have time to get up to full operation temp. Will see how will it works on my way to work tomorrow.

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[Madhorn]

The temp gauge worked better but not as I expected. Then I had a thought. There is no coolant flow across the sensor. So I drilled and taped the into the side of the adapter and ran the steam line to it. Now the temp reads right on the gauge.

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[Madhorn]

Also had time to take a closer look at the drive shaft. Still experiencing a vide/wobble. Had the truck on jack stands in gear so I could visually see what is going on. Could see the wobble. After i shut down the truck I started to flip the drive shaft around just for grins. Thats when I noticed that one u joint would slide back forth even though caps were torqued down. Now I am scratching my head. So I removed the drive shaft and measured the u joints cap to cap. 3.160. Then measured a u joint from the old shaft. 3.224. What I found was there is supposed to be a small plastic bushing in each cap. Several were missing!!! So with new u joints installed the vibe/wobble is gone. Sad thing is that this is a new drive shaft with new u joints.

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[Madhorn]

After a couple months without a stereo we now have tunes!!

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[rpcraft]

Well, **** man, sorry about that. I guess that is one of those differences very few people find out...

 

[Madhorn]

I was beginning to think I had some serious problem in the transfer case, but after finding the u joint issue I am very relieved. Actually ran down the highway at 70 this morning. Couldn’t do that before. The truck is a pleasure to drive again. Made an appointment to have the exhaust done Friday.

 

[rpcraft]

Great to hear man. It's a shame you had to spend the extra time with the driveline stuff but at least it worked out in the end.

 

[Madhorn]

Have been having problems with the drives side window not wanting to roll up. With the door panel removed I saw that the window track frame spot welds had broke allowing the glass to fall out its track. Nothing a couple welds couldn't fix.

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[Madhorn]

Finally. The exhaust is done. Delta flow Flowmaster 40s sound great.