T&T: Fluctuating oil pressure guage on Ford-Lehman 135

[Vance Nelson]

The gauges are probably tied together in series with the sender, so that is
why they would read alike.

It could be as simple as a wire that is breaking off.  The vibrations of the
engine will enhance or dismantle the connection.  Wiggle the wire on the
sending unit and other connections.  You may find the problem.

I had a problem with a wire for my tach - same symptoms as with your oil.
If the alarm does not go off, but the gauges go to near zero, it may not be
a sender.

Vance Nelson
Superior Dreams - GB32-340

-----Original Message-----
From: trawlers-and-trawlering-bounces at lists.samurai.com
[mailto:trawlers-and-trawlering-bounces at lists.samurai.com] On Behalf Of Bob
McLeran
Sent: Tuesday, June 03, 2008 6:33 PM
To: T-T&T List
Subject: T&T: Fluctuating oil pressure guage on Ford-Lehman 135

After checking the engine and transmission oil on Sanderling this 
morning, we got underway from our overnight anchorage off the Potomac 
River. After about 1/2 an hour, while running at cruising rpm (1600) the 
topside oil pressure gage started rapidly fluctuating +/- 15 psi from 
it's normal 45 psi (I think those gages read psi). The inside gage was 
doing the same, so assume the fluctuation was coming from the sending 
line caused either by the oil pump or the sending unit or something else.

There were no indications of any oil leaks (or any other leaks) around 
the engine, no strange smells, no unusual noises. The engine seemed to 
be operating normally.

When I checked the oil this morning it was just about 1 quart low; I 
didn't add a quart because it normally reads a little low.

When I varied the engine rpm to 1400, the fluctuations stopped for a 
short while then started again, but not as variable. At 1800 rpm the 
fluctuations were more exaggerated than at 1600 rpm. After about an hour 
it quieted down to normal, then started up again about four hours later, 
then stopped again.

After we took a mooring in Solomons and after the engine had been idling 
for 10 minutes or so, I revved it up to 1800 and it started fluctuating 
again.

Any ideas about what might be causing both gages to rapidly oscillate 
like this?

-- 
<><><><><><><><><><><><>Mozilla Thunderbird<><><><><><><><><><>
Bob McLeran and Judy Young                  Manatee Cove Marina
MV Sanderling                               Patrick Air Force Base
DeFever 41 Trawler                          Melbourne, Florida 
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