Oil pressure/gauge question 71 C-10

[Hennyhog]

Howdy,
Bought a 71 C-10 a few months ago and going through it step by step addressing once issue after another. The one highest on my list right now is oil pressure/temp issue. The gauge is not working so any thoughts, ideas, suggestions would be greatly appreciated!

Henny

[Davidf]

So, oil pressure AND temp gauge doesn't work, or just oil pressure, or oil pressure gauge doesn't work and engine running hot. Your post needs clarification for me. But, what is clear is that your oil pressure gauge does not or you have no oil pressure. Let's assume the gauge is not working.

First of all, the gauge is mechanical. Since you are not getting a puddle of oil on the floor board, I can assume there are two possible causes to the gauge to operating:

Most likely: There is a restriction in the copper line feeding oil from the engine to the gauge. Or, the oil passage in the block is blocked. Remove the oil line at both ends and ensure you can blow compressed air through the line. Remove fitting at rear of manifold (in block) and ensure passage is not plugged at this point. Check fittings as well for blockage.

Less likely: Linkage between bellows and gauge pointer/needle is broken/missing.

As for the temp issue, what is wrong/happening?

[Hennyhog]

I'm glad you brought up my sort of double barreled question David and thanks for the info on going about tackling the oil pressure issue.

My temperature gauge is reading albiet on the very low side after a good cruise. I took these photos and think the one that screws into block between the spark plugs is my temp sender. Not sure what the one is that is screwed into intake manifold. Thoughts?

[centuryhouse]

Did you ever figure out what the one on the manifold was, or get your problem resolved?

[Hennyhog]

I replaced the one in the block from a 160 to a 180 and now instead of just barely reading on the temp gauge, she runs slightly below the half way point. As far as the one in the intake manifold I just left it as is. Blew the oil line out (disconnected on both ends), hooked it back up again and oil pressure gauge still does not read.....have yet to disconnect while running to see if it is sending oil through line to gauge but it's next on my list.

[Davidf]

Originally Posted by Hennyhog

I'm glad you brought up my sort of double barreled question David and thanks for the info on going about tackling the oil pressure issue.

My temperature gauge is reading albiet on the very low side after a good cruise. I took these photos and think the one that screws into block between the spark plugs is my temp sender. Not sure what the one is that is screwed into intake manifold. Thoughts?

Normally, the gauge temp sending unit is in the front of the left side cylinder head. The transmission spark control sending unit is in the right side head near the rear. The gauge sending unit wire is green (looks like the one fitted to the manifold in your photo). To verify, simply ground one wire at a time to see which wire causes the gauge to peg full hot.

Edit: The photos are confusing. I can't tell what side of engine the photo with sending unit in head is from. Also, I am not sure if the other photo has the green wire or some other wire from the loose connector going to the sending unit. Either way, the factory setup did not have a sending unit the manifold. I believe the spark control sender should utilize a spade terminal. The gauge sending unit a "button" or "nail head" connector (as shown in left photo). Hope this helps.

[Hennyhog]

Thanks for the tip NZC....went home yesterday and pulled line off at gauge, started up & had oil come out of line into a rag so then I goosed a few shots of that air duster can stuff into the gauge to wake it up. Hooked line back up and all is good now.

Davidf,
The sending unit is on drivers side which has the green wire going to it and like I previously stated....it barely registered with the 160 so I went with a 180. Now with the three most important gauges working in the original cluster (oil pressure, engine temp, & fuel level) it's time to fig out why the speedo don't work.

[summitflier]

Originally Posted by Davidf

Normally, the gauge temp sending unit is in the front of the left side cylinder head. The transmission spark control sending unit is in the right side head near the rear. The gauge sending unit wire is green (looks like the one fitted to the manifold in your photo). To verify, simply ground one wire at a time to see which wire causes the gauge to peg full hot.

Edit: The photos are confusing. I can't tell what side of engine the photo with sending unit in head is from. Also, I am not sure if the other photo has the green wire or some other wire from the loose connector going to the sending unit. Either way, the factory setup did not have a sending unit the manifold. I believe the spark control sender should utilize a spade terminal. The gauge sending unit a "button" or "nail head" connector (as shown in left photo). Hope this helps.

I'm pretty sure this is correct for the iron factory heads. For those of us with after market crate engines and aluminum heads... usually we have to go the intake manifold route.

[franken]

I'd disconnect the block end of the line, remove the fitting in the block, and poke a wire in the hole a ways to see if its sludged closed.

[nzc10]

My oil pressure gauge wasn't working on my 72 i just pulled the cluster out and got a air duster and blew the air into the back of the feed on the guage got the needle to move, put the cluster back in and it worked fine

[Davidf]

Speedo should be easy. Remove cable from trans and spin in drill motor to see if needle moves. Can't damage it by spinning in wrong direction, so try both. If needle moves, the issue is in the trans (probably broken drive gear). If speedo doesn't move, then check cable...disconnect from trans and speedo and spin one end or the other. Have a friend verify the other spins. If cable good and trans output good, the issue is wit the speedo itself.

The speedo needle and cable have no physical connection. The cable spins a magnetic "cup" that fits inside a corresponding cup connected to the needle. if the needle does not move, then something is probably jamming the mechanism or the gears have crusty grease that need cleaning off and re-greasing (gears are for multiplication/reduction and odometer).

I would guess your problem is in the transmission. Remove the speedo output shaft/gear and inspect.