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Crashtd420

A 521 in Massachusetts

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Well I decided to check something yesterday that's been bothering me....

My electric oil pressure gauge would drop to zero at idle but my idiot light would never come on... I temporarily installed a mechanical gauge and thankfully I had 40psi at idle..... so next up will be a better quality gauge and sender and I'll be doing something to fix all the things attached to the sender location...... 

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Just now, Stoffregen Motorsports said:

I hate that problem. Electronic gauges have a reputation for inaccuracy.

Probably would help if I spend more than $15 on it too.....

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I have had trouble with the 720 electric oil pressure gauges, it didn't seem to want to move after climbing to 1/3rd of the way up once running, same oil pressure at all rpms, so I put in a mechanical oil pressure gauge and it pegged the gauge and was all over the place depending on rpm, then one day I was fixing oil leaks and I removed the sender, cleaned it up and put it back in and all of a sudden the electric gauge worked great, I think it was the pipe tape I was using on the threads to stop oil leaks which also compromised the ground circuit.

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The senders I'm using have multiple wires so they don't rely on grounding to the block.... 

I just need to buy better quality.... I've been wanting to replace my tach, oil pressure and volt meter with a set from Speedhut but other things keep taking my money..... 

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I just want them to work, I don't care who they are made by.

Mechanical gauges tend to be more accurate for me, but I have 720 wiring harnesses and consoles/gauges in all my 520/521 trucks, they are the electric type, weird thing is that I have had several senders go bad and start leaking oil everywhere, I have never had the mechanical gauge plastic oil line break in any vehicle my whole life.

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5 hours ago, Crashtd420 said:

Well I decided to check something yesterday that's been bothering me....

My electric oil pressure gauge would drop to zero at idle but my idiot light would never come on... I temporarily installed a mechanical gauge and thankfully I had 40psi at idle..... so next up will be a better quality gauge and sender and I'll be doing something to fix all the things attached to the sender location...... 

 

May have only been the sender was bad.

 

Accuracy?? Does it even matter if you have 45 PSI when it's really 50? Or the other way round? Oil pressure varies with RPMs and temperature and why car makers use idiot lights.... it's for idiots that would freak out when the oil pressure drops to 20 at idle. I remember the muscle car era when buyers demanded gauges so we got them alright... with no numbers!!! It worked this way, you got used to what was usual when running.... higher when cold, lower when warm or at idle. What you watch for was something outside the usual. Still works today with an electric. Warmed up and at highway speeds my electric  reads between 55 and 63 could be 50 for all I care but if it started reading 35 I would start checking things. 

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The electronic gauge was showing zero psi at idle, and hooking up a mechanical gauge showed 40 psi at idle. So I'd say that's a big enough variance in accuracy to matter.

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That's a broken gauge or sender like comparing handling characteristics of two different tires but one is flat. I'm talking general accuracy between two gauges, electric and mechanical. Mechanical gauges can fail also. Mechanical gauges also have the  added risk of the pressure line breaking, hopefully in the engine bay and not above your knees. Electric senders can seep oil but not spew it. Perfect accuracy isn't needed or numbers.

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Electric gauge sensors can puke oil, I have had it happen on my work truck at least 2 times in the last 10 years, they start leaking around the plastic and if you cannot see/find/figure it right away it can get way worse very fast.

This leaking shit is one of my things I cannot tolerate with my work truck, I cannot be leaving oil spots/puddles in my customers driveways, especially some of the places I work at.

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Ha ha that reminds me of last week at work. The local town maintenance 5 ton? truck had a cloth diaper tied under the engine. They laughed at me staring at it and said it had a hydraulic leak and that they couldn't get into the shop till tomorrow. It looked like a bed spread.

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I got a good start yesterday morning doing the final install of the ac system... I cleaned up all the holes and sharp edges, then gave a small coat of paint to protect.... 

 

While the paint dried I focused on the wiring, got done to the point I needed to install the under dash unit and i was out of time.....

 

Well for some reason around 730 last night I got a second wind and was able to get out to the garage again.... some how about 3 hours passed and I got about 95% of the install done..... I only have the 2 firewall bulk head fittings to connect, but I need a second set of hands so I can tighten them to the fire wall before connecting the lines..... 

Its amazing how much quicker it goes after it's all planned out and mocked up.... just sucks I need to wait 2 weeks to get it charged now, already spent my allowance for the week....

 

On a side note I was curious if I would in fact be able to feel the air flow from the under dash unit  and that's definitely not a problem....

 

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Sometimes it's hard for me to get started but once started I get into the groove. Often I tell myself that I'll just get this one thing done and quit for the day and it's done so I pick something else knowing I can stop when ever I like. Knowing that I just have to get it done is hard.

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21 hours ago, datzenmike said:

That's a broken gauge or sender like comparing handling characteristics of two different tires but one is flat. I'm talking general accuracy between two gauges, electric and mechanical. Mechanical gauges can fail also. Mechanical gauges also have the  added risk of the pressure line breaking, hopefully in the engine bay and not above your knees. Electric senders can seep oil but not spew it. Perfect accuracy isn't needed or numbers.

As per the hose failure, I almost always use a braided -3AN hose and a bulkhead fitting at the firewall.

 

 

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Well the ac system minus getting charged up at the mechanic is finished..... looks the same as it did during mock up so no more pics. ..

 

I still need to make the final connection to activate the compressor but I'll do that at the mechanic's....

At least for now I have a fan to blow air at me....

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Do you have a pressure switch in the system? Usually there is one to prevent the clutch from engaging if the system isn't charged.

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33 minutes ago, thisismatt said:

Do you have a pressure switch in the system? Usually there is one to prevent the clutch from engaging if the system isn't charged.

Yes there is a binary pressure switch attached to the dryer.....  I did read that the binary switches will deactivate the compressor for both low pressure and too high of pressure,  but I just left the last connection off just incase..

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I build my A/C systems to use both high and low pressure cutoff. My Toyota Land Cruiser LS swap systems use the original high pressure switch with an added binary switch for low pressure, but I am changing my design to use one trinary switch, which is probably what you have. If it has more than two wires, it's a trinary switch.

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13 hours ago, Stoffregen Motorsports said:

I build my A/C systems to use both high and low pressure cutoff. My Toyota Land Cruiser LS swap systems use the original high pressure switch with an added binary switch for low pressure, but I am changing my design to use one trinary switch, which is probably what you have. If it has more than two wires, it's a trinary switch.

I definitely have a binary.. only 2 wires...

Maybe I'm wrong but I keep reading both the binary and trinary have a high/ low cutoff, the only difference is the trinary adds a trigger for fans ... 

 

This was my wiring  reference.....

Screenshot-20190810-130206-Chrome.jpg

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Oh and I almost forgot to add the drain...

 

20190811-174830.jpg

 

The unit had 2 so I just added a tee then ran it out the firewall....

 

20190811-174814.jpg

 

In the engine bay....

20190811-175005.jpg

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3 hours ago, Crashtd420 said:

I definitely have a binary.. only 2 wires...

Maybe I'm wrong but I keep reading both the binary and trinary have a high/ low cutoff, the only difference is the trinary adds a trigger for fans ... 

 

This was my wiring  reference.....

 

I guess it depends on how you set them up.

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2 minutes ago, Stoffregen Motorsports said:

I guess it depends on how you set them up.

I'm sure that's true.... I tried to keep things simple..... 

 

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Oh another random side note.... took the datsun to get food during lunch break, well I want cup holders now..... 

My friend ran back in to get bbq sauce and I dont know how I managed to do it but I knocked his soda over and dumped half of it out onto the passenger floor....

I thought my kid would be the first to do that not me. .  .

Oh well thankfully I was quick with some rags, and the carpet seemed to resist it soaking in.... 

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I am having a friend machine some cupholders out of HDPE (or some other similar material) for a Land Cruiser I am building. They are going to be pretty generic, machined for two cups. If you like, I can get you a pic and a price when they're done.

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