View Full Version : diesel tachometer
Not sure where to post this question, so hopefully this forum will do.
I was curious about up-grading my current dash layout, to include a tach. Currently there's a large fuel gauge to the right of the speedo. And in the LHS pods, there's an M/T spot lower left. I've seen the layouts with the large tach next to the speedo, and the small fuel gauge in the lower LHS. My question is the wiring. Is there connectors incorporated in the harness to do this, or does it have to be fabbed? I've gone back a few pages here, and can't find any info on this. I'm sure it's probably been brought up in the past. Thanx.
(83 C-30, 6.2, dual tanks)
Dvldog8793
09-06-2014, 15:12
Never seen a factory tach in the older 6.2 trucks....lots of gassers had them but I have never seen a diesel.
I have a Tiny-tach in my van that works good and is VERY simple to hook up. DOES not look factory at all but functions very good.
I have an ISSPro in my blazer that was small enough to mount in the open gauge hole to the left of steering column. I looks nice and functions like a regular gauge.
Hope this helps...
Good luck
thanx Dog. Wonder if there's a way to get the factory tach to work on a diesel? I've heard they work off the alternator some how. Have to look into it.
trbankii
09-07-2014, 09:48
Not sure about a factory tach, but Autometer offers these: https://www.youtube.com/watch?v=HhLPAPZxNsM
I also know that there is quite a bit of information out there for converting a gas VW tach to work on a diesel VW engine, such as this: http://www.4crawler.com/Diesel/CheapTricks/Tachometer/index.shtml
You could probably do the same for a gas tach of similar vintage for your C30, but I have no idea how hard it would be to figure out.
Interesting design how the sensor works on the Autometer tach. I'm thinkin there's a better way of attachment than a large worm clamp. I'll have to read up on the VW info. I'ld sure like to make the factory tach work. I have my shop manual, with the electrical schematics, and none of it mentions a tach.
I'm sure there must've been an option on one of the years with the 6.2.
Never seen a 6.2 with a factory Tach
ginger743
09-09-2014, 20:53
If the 6.5 Tach is driven off of the alternator , get a 6.5 alternator and Tach at a junk yard and it seems you'd be all set. May be a problem however with pulley size , " rpm " etc.
Jerry
DmaxMaverick
09-09-2014, 23:13
It's more simple than that. Use a gasser tach (the red-line will be off, but that's what it is), gasser small gage, and a vacuum pump with the pulse generator. Using the alternator as a pulse source will be complicated, as there isn't one that will fit.
If the 6.5 Tach is driven off of the alternator , get a 6.5 alternator and Tach at a junk yard and it seems you'd be all set. May be a problem however with pulley size , " rpm " etc.
Jerry
there's an idea. Will the 6.5 tach mount to the earlier dash/wiring? Is the face color the same? Another possibility to investigate. thanx.
It's more simple than that. Use a gasser tach (the red-line will be off, but that's what it is), gasser small gage, and a vacuum pump with the pulse generator. Using the alternator as a pulse source will be complicated, as there isn't one that will fit.
I have a vacuum pump that does nothing more than drive the oil pump, but doesn't have any generator on it Gregg. This one is a little over my head. I do like the idea of the higher red-line. Seeing I'll be able to spin the 6.2 faster with that tach, I might as well put hedders on it.:D
DmaxMaverick
09-10-2014, 14:17
I have a vacuum pump that does nothing more than drive the oil pump, but doesn't have any generator on it Gregg. This one is a little over my head. I do like the idea of the higher red-line. Seeing I'll be able to spin the 6.2 faster with that tach, I might as well put hedders on it.:D
Never thought of it that way. I don't recommend it, however. I've had one get away from me for too long. I must have hit 5,500 RPM's before getting it shut down. NOT an experience I'd prefer to repeat! The engine survived, but I had doubts about me and the shop for a few seconds (of eternity).
The vacuum pump I mentioned is the same as yours, except it has a connector on it for the tach lead. I'll look around for one, or find a link so you can see it.
The 6.5 tachs are very different. I don't think they are similar size, and they certainly have a different appearance. It might look about as good as a tach duct-taped to the column by the time you're done with it.
The 6.5 alternators are very different from yours. They are designed to be used with a serpentine belt drive, and are stationary (no adjustable mount). You may be able to have yours, or a new/rebuilt alternator modified for tach use.
Either way will require a frequency buffer. The engine/cam driven is simple, 8 pulses per rev, I think. The alternator method would be a bit sketchy, at best, with estimated rational diameters of the pulleys, plus the diameter variation inherent to V-belt pulleys, / the pulse frequency of the alternator.
I think you'd be much better off using a crank sensor (swap in a 6.5 timing cover, add CKP, buffer). Another member here posted up good data on the CKP he was using for an electronic tranny controller. Somewhere in this same forum, IIRC, 6 or 8 months ago.
DmaxMaverick
09-10-2014, 15:12
Here it is:
Tach signal from crank position sensor (http://www.thedieselpageforums.com/tdpforum/showthread.php?t=42389)
You know, this is so puzzling to me, that this dilemma hasn't been rectified. Because a diesel truck usually is considered a "work horse", and a tach is more pertinent to such a vehicle, than a speedo, (well, almost), and there are so many of these vehicles sold, you would've thought this wouldn't even be an issue. Especially, of all vehicles, a CHEVY. Everything is first introduced on a Chevy.
I've not only gathered info from this site, but searched other areas also, and altho there are lots of "potential" installations of factory tachs installed in 80s diesel trucks, none of them were completed successfully. I see aftermarket ones working, and computer controlled 6.5s, but as of yet, don't see any square bodied factory installs. My brother has worked with GMCs for 35 years, and even he had a hard time giving me info. Last nite we did find a Sierra package offered in later 80s with a factory tach, running off the alternator, but it appears to be as rare as 69 Trans Am convertible.
From what I've gathered so far, from everyones posts, is there are many different ways to pick up a signal. From the back of the alternator, to a crank trigger, and also a vacuum pump. But even if this signal materialized, if the ribbon cable going to the back of the factory gauge isn't compatable, it appears there would be no way to connect it. Unless there were an available pin/wire combo in the harness, that could be jumpered to the back of the tach.
Currently, my existing dash layout consists of the big fuel gauge to the right of the speedo, and an empty pod on the lower left under the voltmeter. My dream would be to relocate the fuel gauge to the lower left pod, and have the factory tach, next to the speedo. Seems at this point, if I want the tach, I'll have to purchase a small aftermarket one, and put it in the lower left pod.:mad:
P.S. What about the top kicks, or C-40s or 50s. Is there any potential there? They must've had 6.2s with tachs. Are their dash layouts any different?
Yukon6.2
09-21-2014, 08:15
Hi
I have the small isspro tach.I got a single gauge pod and mounted it on my steering column.My truck is a 90 so there is a protrusion from the column for the blinker stick.Mine is mounted on that,it doesn't cover any other gauges or lights.Been using it for 8-9 yrs no problems.
Thomas
FWIW Review Clark Brothers Instrument Company
http://www.clarkbrothers.net/G_military.html
Catalogs
http://www.clarkbrothers.net/catalogs.html
I think this is going to be very expensive!
Regards
Joseph
trbankii
09-21-2014, 11:54
I've always thought it was a bit odd that instrumentation tends to increase with trim level. The base model in many vehicles gets you a speedometer, fuel gauge, temperature gauge, and a bunch of idiot lights. The "double ultra limited" model gets you the full zoot gauge package.
Further irony is that I tend to find that the person buying the top of the line model is less likely to actually use any of the gauges other than the speedometer and gas gauge - and sometimes don't pay much attention to those either...
Hi
I have the small isspro tach.I got a single gauge pod and mounted it on my steering column.My truck is a 90 so there is a protrusion from the column for the blinker stick.Mine is mounted on that,it doesn't cover any other gauges or lights.Been using it for 8-9 yrs no problems.
Thomas
Checked out the site, and of course there's no pic of the 2" diesel tach.
FWIW Review Clark Brothers Instrument Company
http://www.clarkbrothers.net/G_military.html
Catalogs
http://www.clarkbrothers.net/catalogs.html
I think this is going to be very expensive!
Regards
Joseph
Man their deluxe gauge package looks all business. Nice. (Afraid to look at the prices.)
Further irony is that I tend to find that the person buying the top of the line model is less likely to actually use any of the gauges other than the speedometer and gas gauge - and sometimes don't pay much attention to those either...
I concur 100%.
I wish I knew how to post foreign links, but I don't. But I did find that VDO lists a bunch of electric tachs, and they sell one with a black face, orange pointer, and only 2 1/16th size. I think I could fit it in the small lower left pod, that I believe is where the small factory clock would go. Problem is, they say to hook it up to a "W" terminal off the back of the alternator. I think there's a link showing that this signal can be tapped into either of the 3 diode triode studs. I'm sure my alternator doesn't have a "W" terminal. Does this set-up seem feasible? Their tachs are also available in a 4K or 6K model. The 4K has the 2K reference at 12 oclock, and the 6 has the 3K at 12. Which would be more desirable?
I'm looking at adding a tach to my 6.2 as well, I would go with the 4K as it covers in reality what you will use (if not more), the 6K is overkill imho.
Hello Mike,
My truck has 4.10s in it, W/O an OD, and on the highway, the motor sounds like it's coming unglued at 55-60. I think these things are running somewhere in the 3Ks, so the 6K tach, (270* sweep), would put the needle to the right of the 12 o'clock position on the highway, where the 4K would have the needle almost buried.
DmaxMaverick
09-23-2014, 18:32
I would recommend a tach in the 6K range. With a governed red line of 3600 RPM's, the engine will run at about 3400 under moderate load. It can also (safely) wind up to 4500+ on compression.
convert2diesel
09-23-2014, 20:52
A number of years ago, Dr. Lee posted a DIY circuit board that worked with an engine speed sensor (oil pump drive used in California engines) to give you a signal that could be used with any gasser tach. Found the article in the members area:
http://www.thedieselpage.com/members/features/swangertach.htm
Worked really well for me. Found the drive with the ESS at Rockauto
http://www.rockauto.com/catalog/moreinfo.php?pk=88383&cc=1031151
Hope this helps
Bill
Hello Mike,
My truck has 4.10s in it, W/O an OD, and on the highway, the motor sounds like it's coming unglued at 55-60. I think these things are running somewhere in the 3Ks, so the 6K tach, (270* sweep), would put the needle to the right of the 12 o'clock position on the highway, where the 4K would have the needle almost buried.
Perhaps this would be better, or a 5K if it's a choice. Up to you.
Hey Bill, I like that drive from Rock auto. But I couldn't access the link for the circuit for some reason. I found something interesting from our competitor brand X site. Some-one used a Topkick tach, and said that there's an oil pump drive used in the later 6.2 suburbans used to send a signal to the 4L60E tranny. How obtainable are these units, and would they work for a factory gas tach? I haven't any vacuum accessories, and don't need the pump.
convert2diesel
09-25-2014, 18:19
Joe:
That's the drive I referenced in my earlier post. It is essentially an AC generator and produced a sine wave for the early ECMs. That signal has to be rectified to give you the needed on/off signal to ground that is required to drive a conventional tach.
Tried to find the circuit on my computer but it didn't survive numerous crashes over the years.
The link I sent you regarding the circuit is only available in the members area. Money really well spent. The archives and articles will make your life much easier. Lots of 6.2 info there.
Good luck
Bill
I just checked the members area for something tach related, and gave up after a few pages. It would be nice to have a search bubble.
But I think you answered my question, in that the Rock auto generator will send the correct signal to a gas tach. I guess it's just a matter of making an electrical harness to connect the terminals correctly. I'll have to get a tach, and try to figure out the connections. I see LMC sells gas tachs with the correct face on them. They're a little pricey tho.
Thanx Bill
convert2diesel
09-26-2014, 17:51
I just checked the members area for something tach related, and gave up after a few pages. It would be nice to have a search bubble.
But I think you answered my question, in that the Rock auto generator will send the correct signal to a gas tach. I guess it's just a matter of making an electrical harness to connect the terminals correctly. I'll have to get a tach, and try to figure out the connections. I see LMC sells gas tachs with the correct face on them. They're a little pricey tho.
Thanx Bill
http://www.thedieselpage.com/members...wangertach.htm You have to buy a membership to access this file but it has everything in it to wire up a tach.
You will need this circuit board to convert the signal from the ESS on the oil pump drive. A gasser tach, needs a signal that varies between open and connected to ground like the older "points" type ignition systems.
Again, good luck
Bill
I'm not understanding Bill. The link shows to be on this site, which we are both members. When I click on it, it says URL not found, (or something like that). If you happen to know the thread title, or area on this site where I can access it, I would appreciate it.
Also, I looked in Rock auto, for a vacuum pump for a 1988 6.2 3/4 ton Suburban, but they don't list a 88 Suburban with a 6.2. they only show an available V6, or 305. I can't see a 3/4 ton Suburban, with a V6 in it. I was looking for the pump, to see if it came with the generator harness to operate the 4L60E tranny.
trbankii
09-27-2014, 18:27
It looks like the link got shortened - possibly by the cut and paste. The "..." in the link makes it inoperable.
The full link given before works: http://www.thedieselpage.com/members/features/swangertach.htm
convert2diesel
09-27-2014, 20:34
I'm not understanding Bill. The link shows to be on this site, which we are both members. When I click on it, it says URL not found, (or something like that). If you happen to know the thread title, or area on this site where I can access it, I would appreciate it.
Also, I looked in Rock auto, for a vacuum pump for a 1988 6.2 3/4 ton Suburban, but they don't list a 88 Suburban with a 6.2. they only show an available V6, or 305. I can't see a 3/4 ton Suburban, with a V6 in it. I was looking for the pump, to see if it came with the generator harness to operate the 4L60E tranny.
Joe:
There are two levels to membership on this site. The first is free to all and allows you access to the forums, the other is a paid membership to help support the site and to allow Jim to offer all the print and manuals associated with these trucks. The paid subscription allows you access to the "Members" area (see top of home page).
The 6.2 versions that used that ESS, had a remote mounted, belt driven vacuum pump. The ESS was not used to drive a 4L60E, but rather the EGRs installed on the California spec engines. The 700RV/4l60 (non E) used only the TPS and a throttle Valve cable.
All of these engines, after 93 I think, used a stand alone tranny controller to drive the full electronic transmissions. After they started installing the electronic fuel pumps, the tranny controller was integrated into the ECM.
I have seen a combination Vacuum pump with the ESS that was installed in the oil pump drive but only once, and I think it was on a van. Not a very common application.
Bill
The ACDelco ESS at Rock auto, (p/n 21597), I believe is a replacement oil pump driven unit, to send a signal to the PCM? And doesn't utilize a vacuum pump. As mentioned before, I got info saying it sent a signal to the 4L60 (E?), in the later 80s 6.2s, not the 90s when all the electronics came in. maybe this info is wrong?
I apologize for making this more confusing than it is. But to simplify all the info above, can I just ask this question?
Will the oil pump driven ESS from Rock auto, send the correct signal to a gas tach? (W/O having to modify to electronics of the tach) I realize some sort of pre-fabbed harness will need to be implemented.
(I feel I've already asked this. I'll have to go back and re-re-read.)
Sorry Bill, now I see that you stated the circuit "will" have to be modified to use this drive on a gas tach. Guess I'll have to become a "premium" member, to access this info. Thanx.
So where do I go to sign up? I see the members area line on the top, but that's about all.
convert2diesel
09-30-2014, 19:11
Right beside the "Members Area" there is a subscribe icon. As I said in my first post, this subscription is worth every penny. All of the 6.2 info has been listed in the Members area. If your really interested in some in depth knowledge of these engines, I would also suggest some of the print versions and manuals that Jim and others have collected over the years and have for sale as well.
Bill
Right beside the "Members Area" there is a subscribe icon. As I said in my first post, this subscription is worth every penny. All of the 6.2 info has been listed in the Members area. If your really interested in some in depth knowledge of these engines, I would also suggest some of the print versions and manuals that Jim and others have collected over the years and have for sale as well.
Bill
Agreed, I also got the manuals on my 6.2, all three of them and they were worth the price for them as well.
Alright men, thanx for the guidance. Just got myself signed up. Will have to go through the formalities in a few, but at least the ball is rolling.
OK, so I'm in. I see the article, and it's exactly what I'm looking for. And as old as that write-up is, has anyone come across any alternatives, besides building a circuit board from scratch? I mean, it's pretty ingenious for the author to come up with it on his own, and if I have to make one, I will. I'm thinking there's a bread maker, or some common appliance of some sort, that might already have something useable. It's still beyond me to think this whole tach ordeal is as obscure as it is. If I were to take a pole, how many trucks on this site have tachs in them? 50%? 20%? less?
convert2diesel
10-02-2014, 19:36
Joe:
Total outlay was less than 15 bucks in components (bought many spares due to my soldering skills) and a snowy Saturday afternoon. Trust me, if I was able to build it, you can too.
Talk to the guy at the electronics store. There are bread boards available for prototyping that don't require soldering. Just plug and play and do a bunch of cross wiring. Have no idea how long they would last in this application so that is why I dug out my soldering iron and made three messes and one functional unit that lasted over 100k miles without a glitch.
Good luck
Bill
Bill!? You're the author and builder of this board? Nicely done. You say if you can do it, anyone can? Well, you haven't seem my welds, or solders. They're similar to the snowbanks, I build up, after shoveling my driveway. I have a computer programmer buddy who does some circuit board stuff, so maybe I'll recruit him for assistance, if I get in a bind. We have a pretty large swapmeet that comes around here this month, (Stafford Springs), so I plan on looking for some parts or connections for parts for my truck. Like a rust free cab, or at least a full floor pan. And some cool dash gauges. Maybe that oil pump drive. We'll see what's around. I'll keep you posted on progress, thanx for the advice.
convert2diesel
10-03-2014, 20:35
No Joe:
Can't lay claim to developing this. It was Dr. Lee Swanger (Clevitekid) who did all the work and the one who did the article. I just built one (badly) based on his instructions.
If you're intent on doing a 6.2, do some more digging. He had The Diesel Depot do up a custom 6.2 that put down over 200HP naturally aspirated. Really impressive build and I believe, after over 10 years, the truck is still on the road.
Tried to find the article but no joy. Unless he pulled it, the write up must still be here somewhere.
Bill
As for building a 6.2 past the stock point, I'm a little paranoid.I've had my truck for over 20 years now, and there was a span in the middle of about 5 years, where I had to change out blown head gaskets maybe 4 or 5 times. They blew because of "abnormal" stress, where I was pulling a 5000lb sailboat a couple hundred miles,every spring and fall on the hilly free-way, and the truck didn't like the hi-way wind resistance at all. Had to really work on those long steep up-hill grades. Would've like to have had an EGT gauge, cause I'll bet it was "hot". Also overheated the motor once, which popped a gasket.
Anyway, I hear about people turbo-charging the 6.2s and it makes me cringe. My 6.2 makes 415lbs compression on all cylinders, (or at least it did 15 yrs ago), and as you know are rated 22 to 1, so I can't see how a stock gasket will be able to hold more compression than that. Maybe if the block was o-ringed. As for making more power, "normally aspirated", I've heard people cranking up on the IP, but not sure if I want to give up my "OK" fuel mileage as it is.
This doesn't have anything to do with this thread,(more power), so I don't want to delve into it here, and I'm sure there're other areas to talk about boosting power. But I don't mind a few comments, if you guys/(girls) don't.
I also don't want this thread to be one of those "dead-enders", where nothing gets accomplished. I'm going to make this tach happen , one way or another, so please be patient. Joe
a5150nut
10-04-2014, 10:20
Joe,
If your going to tow invest in a pyrometer. It is very surprising how fast EGT's will climb even empty.
Now that you mention it, if I get a gas tach with a clock in the big RHS pod, next to the speedo, then I can mount the pyrometer in the smaller lower LHS pod, (which is presently M/T), used for the clock option. I saw a dash layout on a brand X site, and someone had a photo of his dash, with the tach. In his smaller lower LHS pod, he had mounted an air pressure gauge from a topkick, to use for his air bags on the back suspension. Looked very functional and factory.
Liftgate
10-06-2014, 15:00
I have been wanting to add a tach to my '84 suburban. It has the california vacuum pump/oil pump drive with the ess socket on it. Does anyone know where I can get a mating connector for that socket other than at the junk yard? Thanks for any help.
convert2diesel
10-06-2014, 19:24
I have been wanting to add a tach to my '84 suburban. It has the california vacuum pump/oil pump drive with the ess socket on it. Does anyone know where I can get a mating connector for that socket other than at the junk yard? Thanks for any help.
Should be a standard two prong male weatherpack connector. Typically your local NAPA or equivalent should have them in stock.
Bill
I have been wanting to add a tach to my '84 suburban. It has the california vacuum pump/oil pump drive with the ess socket on it. Does anyone know where I can get a mating connector for that socket other than at the junk yard? Thanks for any help.
Do you plan on keeping your ESS functional? If you were to incorporate a tach off of it, how will you run 2 connections off your pump?
Went to our local automotive swap meet today, (Stafford Springs Ct), and only saw 3 instrument panels in the place. And there was a pretty good turnout. Lots of "stuff". But out of the 3 clusters, 2 were standard gauge pkgs, and 1 had a tach, with the fuel gauge in the lower left pod. The guy was asking $200. WAY too much for my taste. If it was a diesel set-up, I might've thought about it. I also see the set-ups on E-bay, and the prices are crazy, even for the gas stuff. Guess I'll have to keep hunting.
Supersaloon
02-02-2015, 05:02
There is possibly suitable tachometer pin already in alternator (at least in '90-model) called "P" ("W"), which is connected to the end of field, according to GMC service manual. I said possible, because I haven't tried it yet and don't know if it really works. But anyway FYI :). It is in four pin connector where warning light goes.
http://www.thedieselpageforums.com/photopost/data/500/Alternator-rear.JPG
Connector is that black lump next to Delco, in picture and if I remember correct, P-pin is most upper pin (I don't have service manual or car available right now)
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions Inc. All rights reserved.