Thermostat Housing Sensor Questions...

[LanceVance]

Ok, first a little bit of background; I purchased this engine partially disassembled, and have never had an engine in the shell I’m restoring, so I’m still foggy on where every hose and wire runs. I plan on running MS and EDIS-6 from the get go, using stock gauges, and not running a cold start valve (desert). I also don’t plan on having AC or the heater put back in. When I purchased the engine most of the sensors in the thermostat housing were removed, or had broken clips, which is fine as I would rather have everything in my electrical system new, as I hate chasing down electrical gremlins caused by old/bad components.

 

Pictures!

 

 

 

Now for the Questions;

 

1. I understand that the upper left hole is used for the gauge sender, however this is one of the items removed before I had the engine. I’ve found one on MSA, but it is part of a kit for V8 conversion kit (although it says it is still the stock sensor, just with an adapter) will this work for me? Is there anywhere to just get the sensor? Link Below.

 

http://www.thezstore.com/page/TZS/PROD/PRC01/10-1878

 

2. The upper right hole is used for the coolant bypass. I plan on still running an external bypass, despite there is also an internal bypass, but I’ve had a hard time finding tube fittings in metric sizes. Does anyone know where to get these? What size would I need?

 

3. The lower left hole is used for the Thermotime switch, which I don’t plan on using, but what size is this threaded for? I know that for MS it would be better for me to use a GM style sensor, is this where it would go? Would this be an appropriate sensor? Link Below.

 

https://www.034motorsport.com/034efi-engine-management-engine-management-sensors-gm-style-water-temp-sensor-p-406.html

 

4. The lower right hole is used for fan controls. I have found a Honda sensor that I believe is the correct size and thread pitch, but I’m not sure. It is listed to be used for radiator fans, and has an activation temp range of 70-75 °C, which I’ve read is about where you want it? I plan on using MSA’s duel fan aluminum radiator with this. I would rather not have MS activate the fan, If I can keep it as just having a sensor and not a computer do it. Link Below.

 

http://www.autoparts007.com/oem_37780-PA6-003/Detail_6581_Temperature-Switch.html

 

 

5. The hole on the side is used to adjust timing for the distributor, so I only need to plug this, however I thought it might be cool to use one of these to see the coolant flowing (plus I love spending money needlessly ), what size thread is this? Link Below.

 

http://www.jwwinco.com/products/section12/gn743.2/index.html

 

6. What is this sensor? It was attached to the Thermostat Housing. I’ve searched and come up with nothing:

 

 

7. What is this part called, and where can I get a new one? It was on the other side of the block, and was completely clogged and corroded.

 

 

8. The thermostat housing was taken off when I got it, what size are the two bolts that hold it to the engine?

 

9. Okay, final question! How do I make links without giving the entire address! I’ve seen everyone posting links with one clickable word!

 

Thanks to everyone in advance for your help!

Edited October 7, 2010 by LanceVance

[Tennesseejed]

1. Check you local parts store for the thermal sensor. I found one for $16.

 

2. The coolant bypass connects from the thermo housing to the vertical tube on the doo-hickey shown in picture 7. I found hose at the local parts store. Don't recall the specific size.

 

3. With a two bolt thermo housing (which it looks like you have), the only hole with enough meat around it to tap the 3/8" NPT GM sensor is the thermal sender hole. If you haven't already, download the Megatune/Tuner Studio bundle from DIY Auto and see which sensors are listed under the Tools/Calibarate Sensor settings. The MS software comes with several thermal sensors pre-loaded. It's up to you to figure out the thread sizes for each sensor. And herein lies your potential problem using a two bold thermo housing - If the GM sensor will only tap into the thermal sensor hole, then you will not have a dash temp gauge. I know because this is how it went for me the first go. The second time, I purchased a three bolt thermo housing and, surprisingly, the GM sensor went into one of the holes without tapping. I use two sensors, thermal sender and water temp guage. The other holes are blocked.

 

4. You can also run fan control using your MS box. Using the Honda sensor for direct control is fine, providing you don't need this hole for the water temp sensor.

 

5. I don't know what size threads the side hole has. Sorry.

 

6. No idea what that sensor is. Looks like something off a '78 or a ZX. Did not come on my '75.

 

7. Check the Parts For Sale forum. You should be able to find one of these from someone parting an engine. Don't know what the proper name is. I'd describe it as some sort of coolant collector. FSM digram might have the name, or call a parts store and see what their computers call it.

 

8. Don't know the answer to this, but they have 12mm bolt heads.

 

The best advice I can give when setting up a thermo housing for MS is to decide what water temp sensor you are going to use and where is it going to be located before you do anything else. And don't do what I did, which is to tap the thermal sender hold for 3/8" NPT because you won't have a dash temp gauge.

 

Sorry I couldn't answer all your questions. Perhaps someone else will chime in. Good luck.

[LanceVance]

Thanks for all your input, I wasn't really expecting such a comprehensive list of answers! It seems that my best bet is going to be sorting out the GM sensor first like you said, and then work around the remaining spots and their sizes, I was under the impression it was a direct fit so I hadn't been too concerned with it, but I guess that's just the three bolt housing like you said. Guess I'm going to have to get some definitive answers on the sizes and threads. I'll go to my machinist and have him clean and chase the threads (they need it anyway) and let me know their sizes. Will post up here once I know.

[LanceVance]

Ended up getting a three bolt thermostat housing when I pulled a P90 from the junk yard, and it is much easier to work with! My GM coolant temperature sensor threads right in, as well as the sender for the gauge. Decided to ditch the Honda sensor in favor of using MS to control the fans. I liked the idea of compartmentalization incase I have issues with MS, but I figure having a simple way to control the on temps for the fan makes it worthwhile.

 

Anyhow! I've got one more question now!

 

After reading through the head cooling thread (read it 3 times now, figure three more times and I'll have a decent grasp of it all) I've decided to use the side port on the housing to connect to some lines from taps above the last 2 or 3 exhaust ports. Does anyone know what size thread this is? I would like to run a banjo line (I like banjo fittings for some reason ) to keep it a angled straight back from the housing. If I can keep the original thread that would be great, but if not, what would everyone recommend for a tap size?

 

Here are some pictures of the new housing;

 

 

Side shot;

 

 

And the fitting that was originally in the side;

 

 

Anybody who can help me I out I appreciate it!

[zack_280]

The thread size for the water temperature fan switch in the original post is 1/4"NPT. I was recently trying to figure this out. I didn't find the answer here, so I bought the adapter and it worked. Hopefully this will help anyone else searching.

 

 

*edit: Corrected thread size.

Edited October 16, 2011 by zack_280

[gmgardner99]

For question #8, both bolts are 8mm x 1.25.  They are different lengths with the same thread.