Need temp sending unit OD 5/8 coarse thread
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 42
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From: Seattle WA
Need temp sending unit OD 5/8 coarse thread
My 1980 L82 has a non-stock Wieand manifold - part of a recent engine rebuild. The temp sending plug takes a 5/8" coarse thread OD sending unit. The old unit prior to this last rebuild of the engine is broken so it can't be used (old manifold was also non-stock and had a 5/8" OD sending unit).
I ordered a stock sending unit but its OD (Outer Diameter) is 7/8" so it won't match. I worked with a regional screw/bolt company (Tacoma Screw) but they contacted every one of their suppliers and not one was interested in making a spacer that would drop down in OD and yet be hollow so the fluid would reach the sending unit.
Anyone have any ideas how I could get my hands on a temp sending unit with 5/8" coarse thread outer diameter? If I go to a parts store I just stump the guy as he needs to know the car make/model/year to search for.
Thanks all,
Steve
I ordered a stock sending unit but its OD (Outer Diameter) is 7/8" so it won't match. I worked with a regional screw/bolt company (Tacoma Screw) but they contacted every one of their suppliers and not one was interested in making a spacer that would drop down in OD and yet be hollow so the fluid would reach the sending unit.
Anyone have any ideas how I could get my hands on a temp sending unit with 5/8" coarse thread outer diameter? If I go to a parts store I just stump the guy as he needs to know the car make/model/year to search for.
Thanks all,
Steve
Thread Starter
Intermediate
Joined: Jun 2010
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From: Seattle WA
NPT means? Sorry, a bit of fuzzyness in the old brain this morning. I measured both the ID on the plug on the new manifold, and the OD on the old sending unit (that plugged into the now-retired-and-hanging-from-my-garage-wall old intake manifold) which would screw into the temp plug on the new manifold ok, and they both measure 5/8".
Thread Starter
Intermediate
Joined: Jun 2010
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From: Seattle WA
I understand that pipe thread is measured by the inside diameter - for the longest time I did NOT know that but I was kindly made to understand that recently by a plumber friend. I'm referring here to the OD (Outer Diameter) of the sending unit as it has to thread into the ID (Inner Diameter) of the temp plug on the intake manifold. As I mentioned I have measured both and they are 5/8" coarse thread.
Drifting
Joined: Oct 2007
Posts: 1,317
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From: Marina CA
You have me thinking, the aftermarket sending units (VDO, Stewart-Warner & Autometer) sometimes use sending units with a smaller OD than the stock senders. Do you have the original gauges in your car?
I have an Edelbrock manifold on the 68 and it's water temp sending unit hole is for the larger OD (original) sending unit.
I have an Edelbrock manifold on the 68 and it's water temp sending unit hole is for the larger OD (original) sending unit.
Thread Starter
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From: Seattle WA
Yep original temp and oil pressure gauges but I am replacing the oil pressure gauge with a mechanical one - when I hit the 500 mile point on the engine break-in (yes it's that new) as the old electrical was NOT accurate.
Melting Slicks
Joined: Sep 2004
Posts: 2,655
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Every non-metric fitting I've seen for a temp fitting is NPT, pipe thread. Go to Lowes, get a 1/2" NPT and 3/8" NPT plug. One will fit. BTW NPT is tapered so it should tighten as it goes in.
If your new sender is smaller, just get a 1/2" NPT to 3/8" or 1/4" reducer, about $5 for both.
Also pick up some teflon pipe sealant paste. Use that to have a ghood seal and wont interefere with the senders grounding.
If your new sender is smaller, just get a 1/2" NPT to 3/8" or 1/4" reducer, about $5 for both.
Also pick up some teflon pipe sealant paste. Use that to have a ghood seal and wont interefere with the senders grounding.
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Thread Starter
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From: Seattle WA
Sorry Garys 68 I am not understanding what you are saying here. To me a plug is what is already in the hole in the intake manifold where I need to install the temp sending unit ergo why would I need another one? I need, if I am to use the stock temp sending unit I just purchased (7/8" outer diameter, for 1979-1980), to drop down from 7/8" inner diameter (to accept the sending unit) to 5/8" outer diameter (to thread into the hole on the intake manifold) using some sort of threaded (inner threads on one end, outer threads on the other end), hollow adapter.
Racer
Joined: Aug 2009
Posts: 363
Likes: 72
From: Somers New York
if I am to use the stock temp sending unit I just purchased (7/8" outer diameter, for 1979-1980), to drop down from 7/8" inner diameter (to accept the sending unit) to 5/8" outer diameter (to thread into the hole on the intake manifold) using some sort of threaded (inner threads on one end, outer threads on the other end), hollow adapter.
Last edited by John A F; Oct 21, 2010 at 08:04 PM.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
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From: eastern NC
Steve, is this what your temperature sending unit looks like?
Is there enough material around the existing hole in the manifold to tap it out to the size of your new sending unit? These sending units are definitely NPT and require special taps. Do not try to substitute a standard SAE tap.
My concern with trying to use an adapter that reduces down to the size hole in the manifold is that the sending unit may not reach the water and may even have a small air pocket in the adapter around the probe..
By the way, doesn't the temperature sender in your engine screw into the head between the exhaust ports?
Good luck... GUSTO
Is there enough material around the existing hole in the manifold to tap it out to the size of your new sending unit? These sending units are definitely NPT and require special taps. Do not try to substitute a standard SAE tap.
My concern with trying to use an adapter that reduces down to the size hole in the manifold is that the sending unit may not reach the water and may even have a small air pocket in the adapter around the probe..
By the way, doesn't the temperature sender in your engine screw into the head between the exhaust ports?
Good luck... GUSTO
Last edited by GUSTO14; Oct 21, 2010 at 09:33 PM.
Racer
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From: bethpage NY
Thread Starter
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From: Seattle WA
The intake manifold is a Wieand 8120:
http://www.jegs.com/i/Weiand/925/8120/10002/-1
Where the temp sending unit hole is, is on the drivers side front of the manifold. Passenger side front is a 5/8" inner diameter hole for the return heater hose - I know this because I purchased an adapter at an auto parts store that was 5/8" OD on one end, had a hex in the middle for tightening, and had a lip on the other end for putting the hose on and clamping it down. Both front end intake manifold holes are the same size - 5/8" inner diameter.
Yes Gusto that is EXACTLY my stock replacement temp sending unit - purchased it from Ecklers before I realized it was too big. Also neither Ecklers or Zip had any measurement info for that unit on their web sites.
I've never used a tap and die and am hesitant about getting metal shavings in the cooling system. Good point on the possibility of an air pocket between the sending unit and the coolant. Think I'll keep beating the bushes for a 5/8" outer diameter sending unit.
http://www.jegs.com/i/Weiand/925/8120/10002/-1
Where the temp sending unit hole is, is on the drivers side front of the manifold. Passenger side front is a 5/8" inner diameter hole for the return heater hose - I know this because I purchased an adapter at an auto parts store that was 5/8" OD on one end, had a hex in the middle for tightening, and had a lip on the other end for putting the hose on and clamping it down. Both front end intake manifold holes are the same size - 5/8" inner diameter.
Yes Gusto that is EXACTLY my stock replacement temp sending unit - purchased it from Ecklers before I realized it was too big. Also neither Ecklers or Zip had any measurement info for that unit on their web sites.
I've never used a tap and die and am hesitant about getting metal shavings in the cooling system. Good point on the possibility of an air pocket between the sending unit and the coolant. Think I'll keep beating the bushes for a 5/8" outer diameter sending unit.
Le Mans Master
Joined: Sep 2001
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From: Unreconstructed, South Carolina
hammondo ... suggest install your new sender into the OEM '80 cylinder head ... also, block any unused intake water hole(s) with plug(s) having tapered pipe thread.
Thread Starter
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From: Seattle WA
Spoke with the engine builder - they purchased the current block (Corvette 350 block) for me back in 2000 for another build. They recommend NOT using that drivers side manifold hole as should coolant be low that will be the first place where an air pocket will develop and the sending unit would then not be able to detect any temp.
Their guess on the engine block hole - between cylinders 1 and 3 - is 1/2" NPT and if not it should be 3/8" NPT and said that thread IS tapered so 1/2" NPT = 750-800/1000" and 3/8" NPT = 750-800/1000". Is that engine block hole what was being referenced in those guesses for 1/2" NTP?
Their guess on the engine block hole - between cylinders 1 and 3 - is 1/2" NPT and if not it should be 3/8" NPT and said that thread IS tapered so 1/2" NPT = 750-800/1000" and 3/8" NPT = 750-800/1000". Is that engine block hole what was being referenced in those guesses for 1/2" NTP?
Le Mans Master
Joined: Sep 2003
Posts: 8,812
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From: eastern NC
Their guess on the engine block hole - between cylinders 1 and 3 - is 1/2" NPT and if not it should be 3/8" NPT and said that thread IS tapered so 1/2" NPT = 750-800/1000" and 3/8" NPT = 750-800/1000". Is that engine block hole what was being referenced in those guesses for 1/2" NPT?
If the heads are stock (almost all aftermarket heads now have the hole in the same place) and the sensor is stock it should fit perfectly. The sensor I posted from Paragon and the link mj9311 posted from ZIP appear identical and are for a stock engine. I would wager they will fit in your heads. All you need to do now is determine which head to install it in.
Good luck... GUSTO
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From: Seattle WA
Oops, guess I just don't know my engine anatomy as well as I should - i.e. should have figured you meant the heads rather than the block. These aren't stock heads, they were installed in the 2000 build and I don't have that invoice in front of me and cannot recall offhand what they were but they were still in great shape to be reused for this recent build (side note).
The engine builder mentioned since I have headers it is likely it will be a real bitch (his exact words) to turn that plug. Since I will have to drain the coolant I will probably wait until spring to do this - up here in the NW it's getting close to the time I park it for the winter.
I'd provide pictures but *crap* lost my camera on a hunting trip last week.
Thanks all,
Steve
The engine builder mentioned since I have headers it is likely it will be a real bitch (his exact words) to turn that plug. Since I will have to drain the coolant I will probably wait until spring to do this - up here in the NW it's getting close to the time I park it for the winter.
I'd provide pictures but *crap* lost my camera on a hunting trip last week.
Thanks all,
Steve
