Gauge Cluster Tomfoolery

[Zion]

Although I haven't been on this site for very long, I've got to say that the amount of help I've received from members has been invaluable. In my first post I stated that I have no clue how to work on/maintain an IDI and a majority of my concerns have been mostly my misunderstandings of the nature of the beast. I am now once again in need of some IDI wisdom. For my next Hail Mary of a post, to make a long story short, my gauges are smoking crack.

Here's the rundown of Poltergeist: IDI Edition
​

Oil Pressure
I've got an auxiliary gauge for oil as my dash reads zilch. When the engine is cold, or (what I assume is) at temp/under load, I'm pushing approx. 45 lbs. of oil pressure. Anytime I run low RPMs or idle, the pressure will read between 30 lbs. and 17ish lbs. respectively. When idling at such a low readout, I have experienced no roughness or any other indicators of reduced engine functionality. This leads me to wonder if I'm in for trouble. My suspects are frothed oil, bad oil pump, or (what will be a common theme in this post) my gauge is inaccurate.

Coolant Temp
Once again, auxiliary gauge. I have never seen this truck run close to 180 degrees. It likes to sit right between 140 when tooling around and in the neighborhood of 160 on highway. Having read that most people see their engines running between 170 and 209, I'm not sure if I should worry.

Generator Volts
Pretty sure my batteries are trash. I replaced the alternator (being a 94 IDIT the alt. is already internally regulated) and I still read 10 volts or below. I always give my truck time to recharge after a start, but it always ends up dead after a week or two of operating.

Tach, Speed, and Everything Else
None of them work. On the odd occasion my speedometer needle will do a little dance. The tach sensor on the oil fill is not in good shape and I haven't looked at the state of the speed sensor. My truck is a gas to diesel swap and still has the gas dash cluster + gauges. I'm thinking I might have to tear into the dash and swap/replace some components but I don't have the guts or know-how to do that at the moment. A lot of electrical doesn't work, i.e. windshield wipers, heater, fans. Whenever I get the column into starting position, volts read 8-9, then the dash makes a bunch of random clicking noises and I'm up to my usual sub-par of 10 volts. This clicking continues when using my headlights, and they flicker in synch with the clicking.

I apologize for this being longwinded and quite expansive, but the only machines I know how to work on are either extremely old with little wiring or agricultural. I figure as long as the engine doesn't decide to have a chat with saint peter anytime soon I won't be in store for a money pit, but paying for college leaves very little war funds to properly repair this truck without a lot of planning, certainty, and budgeting.

 

[Scotty4]

Depending on your transfer case, the borg warners eat the speedo gears and the speedo cable routing can be an issue. The gas tach won't work with the diesel. I would replace the headlight and wiper switches as mine were acting up too. And also, do the headlight relay mod to help them out, plug and play easy day.

Depending on gauge make you may have a faulty gauge for temp. Oil, I run between 10-12 psi when the engine is warm at idle. Cold it is a lot higher of course with the advance.

Have you checked your fuses?

 

[The_Josh_Bear]

Oil pressure: seems pretty normal. These are high FLOW oil pumps and so idling in the high teens is OK per Ford service manuals. You'll have better readings if you move the sensor to the oil galley ports but it actually sounds like the gauge is right on.

Coolant temp: kinda sounds like someone removed the T-stat to me. Does it take forever to get up to 140*? Can you heat yourself out of the cabin or is it just warm?

Alt: get a multimeter and see what your true charging voltage is and go from there. The dash unit is crap and I'd love to find a mod that makes it accurate.
Recently I got a few cigarette adapters that show voltage and have two USB ports for charging cables. It's awesome! Always know your voltage and have two fast charge ports to boot.
https://www.amazon.com/dp/B01M9IKYVH?ref=ppx_pop_mob_ap_share

Can't help much on the rest of the dash. I have an 89, don't know much about an OBS. Sounds like you have wiring to do. Check your grounds! Thats the first and most important thing for dash wiring.

Make sure to get a multimeter if you don't have one. Can't troubleshoot batteries or alt or electrical gremlins without one.

 

[Zion]

@The_Josh_Bear
I have no clue how to quote specific texts yet, but in terms of how much heat I'm experiencing in the cab, I can't really tell due to the fact that my fans and heater don't appear to be functioning. If I start driving right from a cold start, going easy on the engine due to temp, it'll take about 5-10 minutes to start developing a temp reading. Soon after, it reaches its comfort zone and stays there. The fella I bought the truck from said he has replaced the sensor in the radiator, but left me in the dark as to what that meant.

 

[IDIBRONCO]

The fella I bought the truck from said he has replaced the sensor in the radiator,

If it is there, it's in the wrong location. It should be in an engine port so that it reads the engine temperature.

 

[The_Josh_Bear]

@The_Josh_Bear
I have no clue how to quote specific texts yet, but in terms of how much heat I'm experiencing in the cab, I can't really tell due to the fact that my fans and heater don't appear to be functioning. If I start driving right from a cold start, going easy on the engine due to temp, it'll take about 5-10 minutes to start developing a temp reading. Soon after, it reaches its comfort zone and stays there. The fella I bought the truck from said he has replaced the sensor in the radiator, but left me in the dark as to what that meant.

Just find a post you want to reply to, and click the "QUOTE" button in the lower right corner of that post. It will insert the post to the compose message box. You just start typing after all the quoted text.

FWIW there are no sensors in the radiator so I dunno what he meant by that either!

 

[IDIBRONCO]

FWIW there are no sensors in the radiator so I dunno what he meant by that either!

When I read that, the first thing that came to mind is the GM radiators with the low coolant (?) light in them. Someone could have rigged one of those in his truck and then installed a coolant temp probe. It seems like a lot of work, but a new radiator costs a lot of money and I've seen worse.

 

[Zion]

Just find a post you want to reply to, and click the "QUOTE" button in the lower right corner of that post. It will insert the post to the compose message box. You just start typing after all the quoted text.

FWIW there are no sensors in the radiator so I dunno what he meant by that either!

Gotcha, I already have a very limited familiarity with these engines and the vehicle in question is a gas-to-diesel swap. Appears to me that the previous owner who did the swap took a few deep breaths off of the tailpipe and then proceeded to start wrenching. Honestly can't make heads or tails of what's going on under the hood.

 

[franklin2]

Don't worry about the original gauges not working. They never worked that well in the first place. Aftermarket add-on gauges are the best way to go.

My engine doesn't have very high oil pressure either, and it has run this way for years. Keep driving it.

Diesel engines are very efficient. This being the case they take forever to warm up if they are not loaded. If you let it idle in the driveway on a cold morning it will never fully warm up. The only time you will see 190 and above is when you have a load on it, or a hot summer day.

On the charging system, you should have a decent voltmeter. With the engine idling, put the meter directly on one of the batteries. Rev the engine a little bit, you should be reading around 13.5 volts or a little higher. If you are reading something less than 12v, your alternator is not charging.

Since you are having so much trouble with the cluster. with the engine idling, take your meter and put one lead on the negative battery terminal, and take the other lead and probe the lightgreen/red wire on the regulator. You should have 12v on this wire. If you don't, that is why it's not charging. This wire comes from the ignition switch via the cluster charge light, and is what turns the alternator on when the key is turned to run.