1985 Fiat x19 Thermostat

It is good to find a specialist you can trust, does good work, and is reasonable.

Is the Costa Mesa guy "Tiki"? He is the only one that comes to mind, although I'm not sure if he is still there - it's been several years since I talked to him.
 
Okay I’ve finally gotten around to reading everyone’s opinions so i believe it’s narrowed down to two options:

Option 1: I swap my current x19 thermo housing with MWB for a 128 thermo housing and have a bung welded and threaded for the temperature sensor.

Options 2: I swap current x19 thermo housing with MWB for a Strada thermo housing (https://www.midwest-bayless.com/FIA...-strada-ritmo-wfuel-injection-1980-on-oe.aspx ) WITH threaded temp sensor port and attempt to search for a upper port hose.
 
welding to the alloy type and thickness that the thermostat is, isn't easy, option 2 ,that I suggested in the begnning, is definitely the better option.

SteveC
 
Don't forget option #3, which is even easier. Add the temp sensor to the block (correction*, HEAD, not block) by retaping the existing hole. Then no welding is needed and the 128 housing and hoses will work as is.

EDIT: Correction, I meant to say on the head, not the block.
 
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Dr.Jeff said:
Don't forget option #3, which is even easier. Add the temp sensor to the block by retaping the existing hole. Then no welding is needed and the 128 housing and hoses will work as is.
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There is no existing temp sensor hole in the engine block for him to retap.

Option #3 would be to fit a short section of pipe with a sensor bung on it to the upper radiator hose, as we both previously noted.
 
What's the size & thread pitch of the FI ECU temp sensor? It just dawned on me that I might have one of those "Option #3" pipes in a drawer at my shop.
 
Dr.Jeff said:
Yes there is on a later 1500 block.
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We're talking about the 1981-86 X1/9 1500 FI 10-bolt engine; this is Red128's 1985 engine:

85x19engine.jpeg

Here's a similar 1500FI engine with both sides of the block shown:

1500a.jpg 1500b.jpg

Where is the temp sensor port on the block that you're talking about? Can you point it out for us in the photos?
 
Jeff Stich said:
We're talking about the 1981-86 X1/9 1500 FI 10-bolt engine; this is Red128's 1985 engine:

View attachment 40610

Here's a similar 1500FI engine with both sides of the block shown:

View attachment 40611 View attachment 40612

Where is the temp sensor port on the block that you're talking about? Can you point it out for us in the photos?
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I see where your confusion is Jeff. In post #24 I was referencing the prior discussions in this thread regarding the option of mounting the FI temp sensor on the head rather than on the T-stat housing. That option was discussed in detail, with photographs, in those discussions. When I referred to that option in post #24, I inadvertently said "on the block", when I meant to say "on the head". I've gone back to correct that. Hopefully @Red128 knew what I was referring to. ;)
 
Engine currently.

I attempted to swap the temperature sensor from the thermostat housing with the temperature dash gauge sensor on the head like Dr. Jeff mentioned earlier but the hole is too big. So that option is out.

Now the question is, would the temperature sensor thread perfectly into the strada thermo housing? Or would it have to be fitted or would the hole be too large?
 

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Looking at your pictures (see below), I'm guessing the hole you attempted to put the FI ECU sensor into was for the TTS (temperature time switch - blue arrow)? The TTS switch is larger than the ECU temp sensor (on T-stat housing). Did you try installing it into the other coolant temp (dash - red arrow) sensor hole? It is smaller than the TTS hole. But I'd have to look up the thread sizes to see if that hole needs to be re-tapped to put the ECU sensor there. None of them are to be confused with the oil pressure switch in the block (black arrow).

image.jpg
 
You need the TTS to make the injection system behave, moving the Dash Temp to another position would be a good choice if you can’t weld in a bung on the thermostat housing.

Having the dash sensor as an add on in a tube after the thermostat would be a reasonable compromise, it would show the actual temp of the coolant leaving the engine. The only negative it would have is if the thermostat did not open you would have no indication the engine was overheating.

So far I have never had a thermostat fail closed but that is my experience.
 
Given the lack of accuracy the stock temp gauge often has, adding a aftermarket temp sender and gauge might be a good idea anyway.
 
Red128 said:
I attempted to swap the temperature sensor from the thermostat housing with the temperature dash gauge sensor on the head like Dr. Jeff mentioned earlier but the hole is too big. So that option is out.

Now the question is, would the temperature sensor thread perfectly into the strada thermo housing? Or would it have to be fitted or would the hole be too large?
Click to expand...

As I see it, ignoring the use of an inline pipe/sensor port installed into your upper radiator hose, you could add the FI ECU temp sensor into your system in 2 ways:

1. Leave the TTS & temp gauge sensors where they are. Drill & tap a port in the currently-blank sensor mount (bung) that is right above spark plug #3, & mount your ECU temp sensor there. Run a 128 thermostat unit & radiator hoses as normal for a 128.

2. Leave the TTS & temp gauge sensors where they are. Run a Strada thermostat with your ECU sensor mounted in the corresponding port on the Strada housing (this port should be the right fit for your ECU sensor, since that's what the Strada FI system used as well). Find/fabricate an upper radiator hose to fit on your 128.
 
Given his engine is freshly rebuilt and assembled, I had the impression he was reluctant to drill another port where that blank bung is (see pic below), but that is an option. However why ignore the use of an inline adapter in the hose (as shown in post #13)? That makes much more sense than modifying the head or T-stat housing.

image.jpg
 
Dr.Jeff said:
Given his engine is freshly rebuilt and assembled, I had the impression he was reluctant to drill another port where that blank bung is (see pic below), but that is an option. However why ignore the use of an inline adapter in the hose (as shown in post #13)? That makes much more sense than modifying the head or T-stat housing.
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I fully agree, but every time we've mentioned it, we just got 🦗🦗🦗chirping.

Perhaps I should've written "...since Red128 is completely ignoring the simple use of an inline adapter pipe w/sensor port being installed into the upper radiator hose...", & my sarcasm would've shown through a little more? LOL 😏

It's the easiest & likely the cheapest solution in this case; no drilling/tapping/machining of the cylinder head is needed, the correct 128 thermostat housing & radiator hoses can be used, installing the adapter pipe is simple & the original ECU sensor wiring should reach without modification. But for some reason Red128 seems to be fixated on using a Strada thermostat unit, instead. 🤷‍♂️
 
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Jeff Stich said:
I fully agree, but every time we've mentioned it, we just got 🦗🦗🦗chirping.

Perhaps I should've written "...since Red128 is completely ignoring the simple use of an inline adapter pipe w/sensor port being installed into the upper radiator hose...", & my sarcasm would've shown through a little more? LOL 😏

It's the easiest & likely the cheapest solution in this case; no drilling/tapping/machining of the cylinder head is needed, the correct 128 thermostat housing & radiator hoses can be used, installing the adapter pipe is simple & the original ECU sensor wiring should reach without modification. But for some reason Red128 seems to be fixated on using a Strada thermostat unit, instead. 🤷‍♂️
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Actually your sarcasm fooled me too. :p I thought you were saying you did not like the hose adapter idea.

It may not really matter, but if it were me I think I'd be inclined to fit the dash temp sender in the "hose adaptor" and put the ECU temp sensor in the hole on the head. However I'm not sure it that hole has the exact same thread as the ECU sensor?

But I think(?) mounting the ECU sensor directly on the head might(?) provide a little more accurate engine temp? I know most of the other makes of vehicles I build have it located on the head, not on the T-stat housing or otherwise. I always assumed Fiat just did it that was as a simple (cheap) means of adapting FI to the US cars.
 
Hey sorry Jeff Stich, I'm not intentionally ignoring, I'm just listening to everyone's experienced opinion. This is my first time rebuilding an engine ever and I'd like to do it right. Installing the inlet adapter seems like a quick fix to me.

I wish I had known this would be a minor speed bump or else I would have done what Dr. Jeff said and had the port drilled in above cylinder #3 when the head was at the machine shop. I'm going to give them a call tomorrow and see if they can drill that for me since I'll most likely be taking them my flywheel to be surfaced since I didn't realize to bring it to them when I took them the engine LoL :oops:

Not sure if they'll have to remove the oil pan to catch the shavings from drilling? I kinda used alot of gasket maker even though I had an oil pan gasket just because the oil pan looked a little wavy and some bolts were lost, broken etc..
 
This hole will go into the cooling passages, which are completely separate from other areas. Therefore no shavings can get into the oil system (or the oil pan). So it's not as critical as it would be if we were talking about adding a oil pressure sensor hole.

Naturally you still don't want a lot of metal shavings in the cooling system either, but not the end of the world if a trace amount does. However the machine shop should be able to drill and tap the hole without much shavings going anywhere - there are tricks to help avoid that. So that can still be a good solution.

Those inline hose adapters for sensors are available for different hose sizes and sensor sizes. Look on eBay or AliExpress, and shop around as prices can vary widely. But I've bought them for as little as around $5 before.
 
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