| Author | Message | ||
| Buddy Tennison (Buddyten)
Registered Member Username: Buddyten Post Number: 64 Registered: 7-2005 Posted From: 216.119.188.207 Rating: N/A |
Hey Guys: How hard is it to install a mechanical oil pressure guage in the cockpit area? And what is the process, cost, etc? We currently have an electrical cockpit guage. We also have a mechanical guage in the engine compartment. At least on idle (can't tell when operating going down the road) the difference between the mechanical and electrical guage readings is remarkable. When we had our oil changed last week, the mechanic said he would trust the mechanical guage a lot more than the electrical one. My first inclination was to have him install a mechanical guage, but since their hourly rate at that shop is $80, we felt that if it was not a major process or costly one, we would attempt it ourselves. Please give us any suggestions that you can, and thanks for your help. | ||
| JC Alacoque (Jc_alacoque)
Registered Member Username: Jc_alacoque Post Number: 64 Registered: 7-2006 Posted From: 72.45.68.242 Rating: N/A |
I ran 40 feet of 1/8 plastic line to the dash for a mech. gauge. Works great. JC | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 400 Registered: 8-2006 Posted From: 74.33.51.225 Rating: |
Buddy you can make the electric gauge read the same as the mech. start with a new sending unit(about $12 ) in the oil block on the bus in the rear.add or reduce resistance to to the gauge by coiling the wire in a 1 in loop this the way Eagle done it at the factory and my dash and mech gauge on my Eagle read the same takes a little time to get exact but takes the worries out and I would worry about 40ft of plastic line for sure | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 443 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Buddy, Electric pressure gauges are not inherently incorrect, something is wrong either with your gauge, its sending unit, or your wiring or grounding. This is going to stir things up, but first, how do you know the mechanical gauge is right? Second, personally I wouldn't run 40 feet of plastic tubing under oil pressure. It is hot in an engine room, and lube oil is 20-40 degrees hotter than cooling water. Granted there is essentially no flow in a gauge circuit, but the rear 3 or 4 feet are going to be exposed to about 250 degrees on a regular basis, and I wouldn't want to take a chance on a failure pumping all my oil out, albeit slowly. So, what do you do? Rev the engine up in neutral and compare full rpm pressure readings between the electric and the mechanical gauges, just for comparison. If both gauges are several years old, which is a distinct possibility, throw both of them out, and the sending unit, and buy new ones. Most of the electrics have a hot terminal, and a sender terminal, with the reading dependent upon the current flow thru the sender, which decreases the GROUND resistance as pressure increases. If the engine isn't well grounded to the frame, or any of the gauge connections have high resistance, the reading will be low. Sorry to give an Eagle owner a bad time about grounds, but some electrical cleanup will be a whole lot easier than running a mechanical gauge... FWIW, George | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 444 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Well, I started the post immediately above, then got sidetracked, so Luvrbus's post got in first. Quite interesting, and he's definitely got my vote! I just didn't want it to look like I was a plagiarist! I'll shut up and post this before another one gets inbetween. George | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 667 Registered: 11-2005 Posted From: 208.54.200.121 Rating: N/A |
Before you do anything else screw your oil pressure sender out part way and then back in to clean the threads and improve the ground path. Different metals tend to corrode even in oil and chances are that you are dealing with steel and Al. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1291 Registered: 12-2000 Posted From: 76.68.122.152  Rating: N/A |
Hello Just to play devil's advocate.... What is the fascination with oil pressure? Do you watch this intently in your automobile? At what oil pressure are you going to pull over and delay your trip, only to ultimately find, after great cost and inconvenience, that your measuring devices are wonky and that the engine is fine? Spend a small amount of time ensuring the low oil pressure alarm is working, pull the dipstick periodically, and move on. And, as George points out, what makes you think the mechanical gauge is correct? If you have nothing left to do on the coach, then get these gauges up to snuff, otherwise, spend this time on the other preventive maintenance items that have been neglected by you or the previous owners. happy coaching! buswarrior | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 351 Registered: 10-2006 Posted From: 208.100.193.70 Rating: N/A |
Quality counts , install a SW gage and avoid the VDO as their quality the last 5 years SUCKS. FF | ||
| Austin Scott Davis (Zimtok)
Registered Member Username: Zimtok Post Number: 258 Registered: 9-2006 Posted From: 216.37.73.226 Rating: N/A |
My mechanical gauge reads about 5-7lbs higher then my electrical gauge. So when I look at my electrical gauge I add 5lbs. I'm not going to worry about a gauge that is 5lbs off. If you were to hook up 10 different gauges you would get 10 different readings. If your more then 10lbs off clean up your wire/ground connections and see if that helps. Replace the sending unit if it is still off. But don't spend too much valuable time on it if it's only off by a little. | ||
| David Dulmage (Daved)
Registered Member Username: Daved Post Number: 203 Registered: 12-2003 Posted From: 142.46.199.30  Rating: N/A |
The electrical gauge in my MC-8 reads lower than the mechanical gauge. I wouldn't worry about it as long as the pressure displayed doesn't change significantly from what is indicated now. Dave | ||
| Glenn Williams (Glenn)
Registered Member Username: Glenn Post Number: 161 Registered: 6-2006 Posted From: 216.163.57.205  Rating: |
I just replaced the gauge and sending unit in my MCI 7 with a new MCI factory unit and it reads about 15psi at idle and about 30 at speed. I also replaced the 3psi sending unit. The electric gauge seems to line up pretty well with the mechanical at idle. I have not tried it in neutral at max rpm. I'd just check all of the grounds and make sure the sending unit is good. The sending unit for mine was going to run almost $200 according to Luke at US coach, but he found me an MCI gauge and sender set for $91 instead. My old gauge was basically obsolete. Good luck! | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 402 Registered: 8-2006 Posted From: 74.33.56.175 Rating: |
Glenn,does MCI use something special for a oil sending unit you can buy a sending unit for Eagles at any NAPA store for less than $12 bucks I never heard of a oil pressure sending unit for $200.Buddy if you have the Eagle VDO gauges here's a site for you www.egauges.com to order a sending unit plus a lot of info about trouble shooting (Message edited by luvrbus on May 27, 2008) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 449 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
A couple of more thoughts. 24 Volt sending units ARE different from 12 Volt senders. The vast majority of us have an engine with the fuel injection system inside the head(s) with the lube oil. When a fuel leak occurs, it dilutes the lube oil, and causes bearing failure quickly. At speed, the oil pressure will fall noticeably, but not enough to cause a low pressure light. I don't care if my two readings are off a few pounds, I just want to know when I'm 10 or 15 pounds low going down the road. G | ||
| Glenn Williams (Glenn)
Registered Member Username: Glenn Post Number: 163 Registered: 6-2006 Posted From: 216.163.57.205 Rating: N/A |
Luvrbus, As George mentioned, the MCI's are 24V, but also the sending unit needs to match the resistance of the gauge. In my case, this 40 year old gauge hadn't been made in a LOOONG time, so the senders are out of this world. Glenn | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 403 Registered: 8-2006 Posted From: 74.33.56.175 Rating: N/A |
Glenn, we have a large NAPA store in my area and the guys are good about matching the sending unit with gauge only when you get away from the 4 major mfg do they have trouble.George I lost a engine one time from fuel in the oil and a bad dash gauge so mine is going to be real close on the psi (Message edited by luvrbus on May 28, 2008) | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1154 Registered: 10-2003 Posted From: 71.58.48.228  Rating: N/A |
It can be easy to get unwanted resistance in 40 feet of wire with dirty connections or a little corrosion. Check the accuracy of the gage/ sending unit with a short piece of wire back at the engine. Compare it and it should read the same when installed up front.If it doesn't match with a good short wire, you need to decide what is at fault. Make sure the mechanical gage or electric sending unit doesn't connect directly on the engine, as the vibration can cause failures or eventual innacuracies.Most of the setups have a line going from the engine to a junction block.Make sure that the line isn't coked up with old oil sludge. If you are mounting a mechanical gage directly to the engine, get an oil filled one to resist vibration.Make sure you have a WORKING idiot light and engine alarm/ shutdown system for oil pressure and water temp. You can drive a good distance and not notice overheat or very low or no oil pressure. With only a gage you'll be thinking.....how long has THAT been going on? |
