MG MGB and MGB GT Tech Talk
Is it typical for the oil pressure gauge to range dramatically? Every so often, while cruising down the road I'll look at it and it's nearly at 0, then without any change in acceleration or anything it'll just rise to the mid point, go down and up a little. It seems random... and it scares me every time I see it near 0.
not typical at all. either the gauge or sender is bad, or you have a serious problem. got oil in the sump?
check oil first
tee into the oil pressure line and run a cheap oil pressure gauge into the cockpit and temporarily mount it near the original so you can compare. if the new gauge does the same, it'll probably be an oil pump problem, i'd guess. unless you wait too long..... then it'll be a BIG problem.
Agreed; oil pressure is nothing to take lightly. The direct reading gauges, such as is installed in your cockpit, is fairly reliable. Hopefully it's just your gauge. What does it normally read at startup and at cruising RPM?
My guess is that you have a faulty sender or a bad connection. If your oil pressure was falling to 0 psi I think that you would have found out about it by now. The engine would have seized up or you would have thrown a rod through the block. It would be prudent to hook up a mechanical gauge and then check the oil pressure. RAY
If it is a mechanical gauge then it is unusual for the gauge internals to fail in such a way that you get erratic readings.
If it is the electric gauge - then it is almost surely the sending unit. There are a pair of contacts in the sending unit that wear out or burn - once they do it gets really erratic. But I thought your year was mechanical.
I'll check it out. Where is the sending unit (if it is an electrical gauge)? and where do you recommend I install a cheap secondary gauge (where should I tie it into)?
m
Unless MG installed both electrical and mechanical gauges in '76, it's a mechanical gauge, since that's what I have in my 76.
get a cheap mechanical gauge with a plastic pressure line at autozone or pep boys etc. you should also be able to get a "tee" there. find the oil line at the rear upper right hand[passenger side] of the block, between the dizzy and large oil line. follow the flex line from there to the bulkhead where it ends and connect the new tee there, if you cant find a "tee" disconnect your line there and connect the new line at that point.
You could "T" it right at the anti-run-on pressure-switch connection, if you can get a fitting...It's at the top of the passenger footbox , in the engine compartment....Not sure what the fitting size is, but you can pull the switch and take it to the auto parts store.
Like Terry said, this is the kind of behavior I'd expect if it had an electric gauge. The one in my '68 did this often until I switched it out to a mechanical.
Problem is,'76 cars were mechanical. This is something to get figured out before driving the car again!
Is this the oil sender? If so, is this mechanical or electrical? (If it's not the sender, where is it???)
michael
thats the sender. looks like theres some corrosion around the push-on connector. you might wanna clean that off...and be sure the connection is complete. then restart and check what your gauge sez, before you do the tests we all suggested. and thats where i'd attach the test gauge
Ummm.... isn't that the sender for the carbon can and ARO system? If so, it has nothing to do with the gauge. I thought the mechanical gauges only had a small oil line routed off the block (somewhere)to under the dash.... If so, perhaps the line is kinked/cracked/loose etc??
Follow the flexible line and you should come to a connection to a small solid line. That is the feed line to the gauge.
That is not the sender for the gauge, it is the switch for the anti-run-on...BUT , it is on the oil gauge line where I am suggesting you tap with a separate oil pressure gauge..Just unscrew the switch from the line, and take it to auto parts store for the correct size fitting that can be used with an external gauge.
any way to easily increase oil pressure? I'm using 20-50w, that helped allot but still only low side of 50 on gauge even at 3,000-3500 rpm....would additive help or did I just swear!
any way to easily increase oil pressure? I'm using 20-50w, that helped allot but still only low side of 50 on gauge even at 3,000-3500 rpm....would additive help or did I just swear!
please don't tell me not to drive it!!!
Berkley
go ahead and drive it. i'll bet theres an LBC mechanic that needs the business.
An oil filter that is too short can cause problems with oil flow back into the sump, and thus oil pressure. When I bought my '74, it had a crappy filter on it that caused the pressure to slowly drop as you drove. If you stopped, let the oil drain back , and restarted, it would be fine for a while.
Put a new fikter on, and voilà! Steady pressure!
