www.iFourWinns.com

I have been plagued with some intermittent low oil pressure indications since November. First time was day two of my two day trip across South Florida. 1st engine start of day showed no oil pressure. Shut down after 10 secs. Tried again and same thing. On the third start, oil pressure came up and was fine all day.

A couple weeks later, had low oil pressure on start up, and this time it did not come up with repeated start attempts. Added a qt of oil (which was not low, but near the lower line of the "safe zone"). Oil pressure came up on the next start. This made me quite worried it could be the oil pump, or the oil pump inlet screen assembly. Online forums showed some 5.7 Chevy truck engines could have that problem.

Another week later it happened again, but this time, a couple attempts would show the oil pressure come up and then drop down to zero after a second or two. The next attempt the oil pressure came up and stayed up for the rest of the day.

So I was hoping it was a sensor problem, as the oil pumps are extremely reliable. I ordered a new oil sender, and in the mean time, I borrowed a mechanical oil pressure gage and connected where the oil sender was. To my relief, the mechanical gage showed the oil pressure jump to at least 40 psi on every engine start without any hesitation.

I decided to install a Tee connection with both a mechanical gage hooked up in the engine compartment, and the oil sender going to the VDO cluster. My VDO cluster has been very reliable up to this point, with the exception of a blown fuse one time.

Indications today with both gages attached, showed normal oil pressure reading on the mechanical gage, and indications on the VDO that would erratically change anywhere between normal, low, or zero. Whenever it is zero, or nearly zero, I also get the Low Oil Pressure Idiot Light, and audible alarm. So despite the issues that VDO clusters often have, I am still suspicious of the new sensor, or the wiring. The sensor is a single wire type. It was a Volvo part, not aftermarket.

Anybody have further diagnostic suggestions? Know what the resistance values are for normal oil pressure (and zero pressure)?

At least I can go boating tomorrow and with the mechanical gage, I know I have proper oil pressure because of the mechanical gage, but I will probably have to pull the fuse on the VDO cluster so it doesn't sound the alarm the whole time.

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Were you able to check wiring and ground conections? Also, trace the wires and have someone watch the gage while you tug and move the wiring and connectors. Is it possible to try a jumper wire for the sensor wire and the ground? The alarm and warning light are most likely wired into the VDO cluster's oil pressure circuit. If you can eliminate the wiring as the source of the problem, then it is probably the VDO cluster. Wish I had more answers for you.

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Surface Interval: A scuba diving term for that time between dives to relax and prepare for life's next great adventure.

Current boat: '02 FW 268 Vista
Previous boat: '95 FW 190 Horizon

I have only had time to check the wiring connection at the sending unit (so far). When I get to the back of the VDO cluster, I would like to have a resister on hand to connect and see if it gives the right reading for that resistance.

I have looked for the resistance value at known oil pressure readings. I know LouC has published that information for temperature gauges (448 ohms +- 10% @ 100*F, 128 ohms +- 7.5%@ 160*F, 46.6 ohms +-5% @ 220*F), but I couldn't find it for Oil Pressure gages.

So I just called Faria and got that information from them. For an American Resistance Standard Ground gage and sending unit, the values are:
0psi: 240 ohm
40psi: 103 ohm
80psi: 33 ohm

With that, I can diagnose further.

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Update:
Yesterday I was out boating, and the mechanical gage showed good oil pressure, and the VDO varied from zero to low with the alarm sounding. So I had to pull the fuse on the VDO panel to enjoy the boat ride. 2 hours later, I plugged the fuse back in so I could check the fuel level, and the Oil pressure reading was back to normal (60% of scale which is probably 50 psi). Left the fuse in for the next hour without a problem.

So I guess this will be an intermittent problem. I'll get it sorted out eventually.

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Ray, I looked in my OMC shop manual and it doesn't give ohm readings for the oil pressure sending unit like what you got from Faria.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Thanks for checking Lou.

This was posted before by tymorrissette, but I'll list it here also:
http://faria-instruments.com/site_manuals/IS0085E.pdf
That is the listing of resistance (ohms) for all sending units as published by Faria

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I know this thread is almost three years old but am real curious as to what the final outcome was. I have exactly the same issue with my 99 Sundowner 245 with the 5.7 GSI. Same symptoms at dash and same audible alram. Engine seems to run fine with no odd sounds or overheating. Have not tried the mechanical guage yet but plan to do so next time I am up to the river where it is stored-Sweetwater Landing in Ft Myers Fl

Unfortunately, I do not have a final outcome. This intermittent problem occurs once in a while on startup, but has been going away and not troubling. So I have not been inspired to spend more time on it.

I am still glad that I also have a mechanical oil pressure gage in the engine compartment that I can always count on.

Ray

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Thx for the reply. Looks like lots of people have had issues with the VDO display on these boats. I have yet to get up to mine to do some tinkering to figure out if I have a sensor, display or bona fide oil pressure issue. The marina did do an oil analysis and other than some minor contaminant issues it did not indicate bearing issues. I suspect strongly the sensor is bad but will not know for sure until I can put the mechanical gauge to it. Where exactly did you mount your mechanical gauge in the engine compartment? Your boat has basically the same setup as mine minus the cutty cabin. Did you try adding the additional ground wire to the display as others apparently have?

Just to follow up on this. I was able to get to the boat yesterday. Started it up several times to verify I still had the low pressure and telltale warning. I did. Got to the back of the engine and took to the sender behind the distributor. Was a bear to remove because of the access and the fact that it just did not want to come off. Ended up breaking it off so I could remove it and the fittings connecting it to the engine block. Fitted the mechanical oil pressure gauge and sure enough, the pressure was right where it should be. Fitted a brand new oil sender connected up the wiring and the VDO oil gauge came to life! In the meantime, I contacted Dave from AA Marine about the replacement Faria separate gauge dash replacement. AA still makes these and I will order one simply because they look much better and much easier to adress issues with should something go wrong with an individual gauge in the dash. Incidentally, Four Winns said they no longer stock these.

good outcome!
Believe it or not my boat still has the original Medallion gauges and they all still work. I actually have a new set of Faria gauges but as long as the old ones work I can find other more critical projects to do. However, you must have working gauges!

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Yeah, I agree. I did not feel confortable with an unreliable oil gauge even though I suspected the oil pressure was “probably” not an issue. Will probably keep the original dash in for a while as I too have other issues that need attention. Just want to make sure though when the time comes, I have an alternative in place before the sources for these dry up!

I installed the new FW gauge panel I received from A&A Marine. Removing the old panel on my 99 FW 245 Sundowner was pretty easy. Four plastic wingnuts hold the panel from behind. Once these are removed and the 24 space AMP harness connector is unplugged, the panel comes out from behind. The woodgrain trim surround pops right out. The new panel is installed by first drilling two small pilot holes through the top of the new panel. Locations for these holes are pre-located in the new panel. Once this is done, the panel is inserted into the dash opening and adjusted so that it fits evenly. A drill is used to put two holes in the top inside of the dash binnacle that coincide with the two pre-drilled pilot holes in the trim surround. After fastening the new panel, the 24 pin AMP connector is mated to the boat wiring harness removed during removal of the old gauges. That’s it! All guages came to life as soon as the engine was started up.

Great! post up some pix if you can so we can see the end result. Winter cover is still on our boat hope to remove it in the next month or so.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Can’t figure out how to post photo!