I have had a recurring problem with the CHT sensor in my '75 1.8. The threaded "port" in the cylinder head was stripped when the sensor was inadvertently installed at an angle during an engine rebuild. We tried a threaded insert with lock-tite but that didn't work either because the hole is too large for the threaded insert to bond properly. The CHT sensor works its way out of the hole and creates havoc.
Since the cylinder heads are identical on both sides of the engine, there is a port on the opposite side but not in the same orientation (closer to the firewall). It's likely that this hole has never been used and would be in good shape. I could drill a hole in the engine tin for access and use this "port" for my CHT. Of course, I'd need to lengthen the wire so that it would reach the connection on the harness properly. All of this could be done with the engine in the car. I don't show it in any concours events so I'm not particular about its appearance per se.
Anyone see an issue with doing this? Thanks for your input.
Full Version: CHT Sensor alternate location
the opposite side head will have a boss where the CHT would go.
It is relatively easy to drill & tap, but I did it with the engine out of the car.
It is relatively easy to drill & tap, but I did it with the engine out of the car.
Harve, did it work it's way out again since we put it back in at Amelia?
If not, I'd see if it stays this time. I gave it a good tug when I put it back in.
If not, I'd see if it stays this time. I gave it a good tug when I put it back in.
QUOTE(57lincolnman @ Mar 25 2015, 01:22 PM) 
I have had a recurring problem with the CHT sensor in my '75 1.8. The threaded "port" in the cylinder head was stripped when the sensor was inadvertently installed at an angle during an engine rebuild. We tried a threaded insert with lock-tite but that didn't work either because the hole is too large for the threaded insert to bond properly. The CHT sensor works its way out of the hole and creates havoc.
Since the cylinder heads are identical on both sides of the engine, there is a port on the opposite side but not in the same orientation (closer to the firewall). It's likely that this hole has never been used and would be in good shape. I could drill a hole in the engine tin for access and use this "port" for my CHT. Of course, I'd need to lengthen the wire so that it would reach the connection on the harness properly. All of this could be done with the engine in the car. I don't show it in any concours events so I'm not particular about its appearance per se.
Anyone see an issue with doing this? Thanks for your input.
Good idea; would you post some pics when you install it.
QUOTE(ThePaintedMan @ Mar 25 2015, 01:17 PM)
Harve, did it work it's way out again since we put it back in at Amelia?
If not, I'd see if it stays this time. I gave it a good tug when I put it back in.
George, the CHT is holding nicely now. However, this is the 3rd time that this has happened. I will drive the car for awhile to see if it acts up again. Fortunately, when it happens it is gradual. I wanted to see if there's another permanent solution to consider.
Thanks again for all of your help. ThePaintedMan rocks!
QUOTE(jim_hoyland @ Mar 25 2015, 04:15 PM)
QUOTE(57lincolnman @ Mar 25 2015, 01:22 PM)
I have had a recurring problem with the CHT sensor in my '75 1.8. The threaded "port" in the cylinder head was stripped when the sensor was inadvertently installed at an angle during an engine rebuild. We tried a threaded insert with lock-tite but that didn't work either because the hole is too large for the threaded insert to bond properly. The CHT sensor works its way out of the hole and creates havoc.
Since the cylinder heads are identical on both sides of the engine, there is a port on the opposite side but not in the same orientation (closer to the firewall). It's likely that this hole has never been used and would be in good shape. I could drill a hole in the engine tin for access and use this "port" for my CHT. Of course, I'd need to lengthen the wire so that it would reach the connection on the harness properly. All of this could be done with the engine in the car. I don't show it in any concours events so I'm not particular about its appearance per se.
Anyone see an issue with doing this? Thanks for your input.
Good idea; would you post some pics when you install it.
Sure.
My 1.8L had the CHT broken off and I couldn't get it out. So I put it on the #1 cylinder and cut out a hole and put a patch on the #3 CHT hole.
See it here:
Spoke's Progress Thread
See it here:
Spoke's Progress Thread
I'm sure it will work on the opposing cylinder head but the reason it is located on the 3/4 cylinder head is because the #3 cylinder is typically the hottest running cylinder on the engine. At least this is the case on Type 1 engines and I believe the Type 4 is the same. Anyone else have any knowledge about the temp censor location?
Yes, that is why it's there. You could install one like the bus engine's where it is in one of the tin screws location. You would have to drill and thread it.
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