Putting in a replacement L-28

[Zed Head]

3 hours ago, Av8ferg said:

So, I’ve mostly had a good experience with them.  The reality is I’ve has some issues with all the Z retailers.  Zcardepot sent my the wrong tie rod and it was a pain to get them to sent me a replacement.  They wanted pictures and multiple detailed explanations.  I finally sent them a video showing the treads were for the wrong side, the whole process took over 3 weeks.   Then they asked me to send it back on my dime.  I never did and won’t.  Anyone need a drivers side tie rod 😁. 
 

I just want MSA to update their website to show things that back ordered or send you and email and ask how you want to proceed.  It’s simple, be now we are living in a world where the customer is no longer as valuable as the past.  You are almost a nuisance to some.  It’s hard to find quality people.   This is the new paradigm we have to live with.  I see it everywhere I go.  Prices are insane everywhere., workers are worse than ever…the sky is falling 🤣  
 

@Joseph@TheZStore @Greg@TheZStore @James@TheZStore

@zcardepot.com

[Zed Head]

1 hour ago, Av8ferg said:

Dave, this sensor is not intended to be in coolant like the 280z one in the thermostat housing. It’s a dry sensor. Speculation talking with people with more knowledge than I think Nissan moved this sensor to the head to get a better indication of engine operating temp back where cooling is least efficient. The back of the engine being hotter by the mere fact it gets less air flow and coolant will likely take the path of least resistance nearer to the pump making the engine cooler up front. You have to assume Nissan kept trying to improve the engine and this was one iteration of this process. It’s only a guess.

Other manufacturers have moved to dry cylinder head temperature sensors.  I have a Ford that has one and they actually use the reading for the "coolant temperature" gauge in the dash.  And, it turns out, they just set the needle in the middle if the temperature fits within a wide range.

Anyway, on the Z's Nissan went to the head sensor with the P79 and P90 heads in the ZX's. They look almost identical.  The part numbers differ by one digit.  Actually, now I see the difference.  But I think that they have the same thread and can be interchanged.

I accidentally pulled the guts out of one of mine trying to remove the connector.  It's just a dry hole with a thermistor and silicone gel inside.

Edited November 10, 2021 by Zed Head

[Dave WM]

so you think it can be interchanged with a stock 75 ECU? vs a ZX ECU? Just relocate the wire harness and install a dry? the reason I ask is the dry sound like it may be more reliable than the one that is exposed to coolant. 

[Zed Head]

The resistance versus T is the same.  Fitment would be the issue, I'd guess.  Might be that Nissan just modified the connection part because it had a tendency to fall apart like mine did.

From the 1980 EFI book.

[Av8ferg]

I plan to use the same 280z ECU that’s in my car.  The single should be the same so I don’t think I’ll have a problem

[Av8ferg]

8 hours ago, Zed Head said:

Hope you guys don't mind, I'm going to "at" the MSA guys and ZCD.  ZCD never responds but I think that he does read the posts.  The guys at MSA usually respond, and seem to address issues.  The penny-saving on shipping seems like a new one though.

@Joseph@TheZStore @Greg@TheZStore @James@TheZStore

In MSAs defense they are the best overall place to buy Z parts, in my opinion.  They actually answer the phone, are very friendly and willing to answer questions.  It’s hard to be good all they time,  I’m just frustrated because I was just left in the dark for about 26 days, waiting on a part to be coated.  A part I could do without but not the other stuff.  
Oh and try calling zcardepot….they never pick up, you get voicemail and it can take days for a email reply.   Both places have a good selection of parts and competitive prices.  I default to MSA because I can talk to a human if I have a question and they’ve all been super nice.  

[Zed Head]

The main reason I let them know is so that they don't have a problem that goes on for months or years, damaging their business, because they did not know about it.  They've been around since land lines but things are changing.  Trying to help them keep up.

 

[Captain Obvious]

10 hours ago, Zed Head said:

Anyway, on the Z's Nissan went to the head sensor with the P79 and P90 heads in the ZX's. They look almost identical.  The part numbers differ by one digit.  Actually, now I see the difference.  But I think that they have the same thread and can be interchanged.

I don't know about the aftermarket stuff, but the original OEM ZX sensors are a little different in the way they mount... On the Z version, the brass body portion is all one piece and the electrical guts are crimped to the body to finish the assembly. In contrast, on the ZX version, the tightening nut spins independent of the sensor body. The "body" portion is two distinct and separate pieces.

Why does that matter? Because if you use a ZX version with the spinning nut in a wet location like the Z thermostat housing, it will probably leak through the seam between the body and the nut. You could probably use a Z version in the side hole in a P79 or P90 head, but I would be wary of the converse of using a ZX version in a Z thermostat housing.

That pic above of the aftermarket ZX sensor looks like it's made pretty much the same as the Z version, so who knows?

Oh, and the connector key is in different locations between the two of them. Not an insurmountable issue, but something to be aware of.

[Captain Obvious]

I just nabbed a pic off rockauto that shows the original ZX version with the spinning body:

That said... The part above was the only one that looked like that. Most (all?) of the other aftermarket stuff looked like it did NOT have the spinning nut and could be used in either a wet or dry hole.

[Zed Head]

38 minutes ago, Captain Obvious said:

That pic above of the aftermarket ZX sensor looks like it's made pretty much the same as the Z version, so who knows?

I agree.

But thanks for clarifying, I think that you are right,  Obviously.  Now that you bring it up, I do remember the bottom "spinny" portion on the ZX parts.  So, maybe, probably, it's just a one-way possibility.  You can put a Z sensor in a ZX hole but you can't put a ZX sensor in a Z hole.  Or maybe you can't do either, although I think that Av8ferg did, if I read his words correctly.  He should be just fine, right?

I was surprised at the prices.  Things are getting expensive in Z world.  So, a one-way swap, Z part in ZX hole, looks reasonable.  Might help the wrecking yard and CL searches also.

[Captain Obvious]

I think the reason they did the spinny nut on the ZX version is for better thermal conductivity between the head casting and the sensor tip. I think sensor tip is designed to bottom out in the dry hole against the aluminum of the head. And they did that spinny nut thing so you weren't scraping the sensor tip as you tightened the nut. You could hold the sensor from rotating while you tightened the nut.

Of course, that would also make it such that the spinny nut would not necessarily bottom out against any sort of sealing washer. I wonder of they used an O-ring seal there instead of a brass crush washer. I've got some ZX stuff around here someplace and if I can find it, I'll take a look.

In any event... If you filled the hole with thermal conductive goop it would probably be fine. I can't believe the head temp changes that fast and I can't believe there would be a huge thermal gradient between the head and the sensor regardless if it bottomed out or not. But I wasn't there when they designed it.

[Zed Head]

That's a good summary.  The aftermarket guys probably went cheap on their design and just grind the tip in to the bottom of the hole or let it sit above the bottom, not contacting.  I was wondering about the washer also.  No point to it if the sensor tip is supposed to make contact.