Low oil pressure reading on gauge--why?

I have a 1991 extra cab pickup with a 22RE engine. It is a 5 speed manual with about 134k miles on it. I've had no problems with it but now I've noticed the oil pressure gauge registers a low reading when I'm driving.

The gauge used to hover around the middle range but now hovers around the "L" end except for brief sweeps into the middle range but then it drops back down to the lower "L" side.

My questions are:

1) what can cause this? 2) What troubleshooting steps should I take to determine the cause? 3) Has this happended to anyone else and what did you do to fix it? 4) Could it be a bad sending unit?

I use Castrol 10W30 oil and change it religiously at 3,000 miles and use a Toyota filter. It drives fine despite the low oil pressure readings but it worries me.

Thanks in advance for any advice/tips...

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Reply to
Yoboslayer
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I don't know if you've had any success figuring this out but I thought I'd issue a warning.

I have a '94 xtra cab, 22RE engine, 5 spd. manual, 100k miles. For the last six months / year I've noticed the same oil pressure behavior that you describe. I knew the oil had been changed at the appropriate times, and I could tell I had plenty of oil on the dipstick (and clean oil, too.) I thought maybe it was just a bad sending unit, something screwy with the electrical, etc.

I also noticed a reduction of power at low rpm/idle. I thought maybe it was time for a new battery or alternator, or maybe a tune-up.

Then a couple of days ago my timing chain broke while driving home.

I don't think I had any other warning. I certainly didn't hear anything unusual.

I don't know if the oil pressure reduction might have been related to the timing chain issue. I've heard that the chain guides can crack and fall into the pan, screwing up oil distribution. That might explain the lower oil pressure, I suppose.

Reply to
Dave

A lot of time 10w30 is not enough in a older engine in hot weather. You might try 15w40 in it and it should boost oil pressure 5 to 10 PSI or more when hot. (Do not use 10w40)

Reply to
SnoMan

Why don't you start with a tee adaptor on the oil pressure fitting, and get a good quality direct read gauge. These gauges in the truck depend on the sending unit and a level voltage. I'm not so quick to think pressure is low till I see it. check pressure when cold, and pull over, pop the hood anything the engine is hot and you wonder. You could install a line to an underdash mechanical oil pressure gauge if you're so inclined, but once you know what you need to know, you could remove the tee-adaptor and save it will you need to check again

I'm a 5w-30 kind of guy, and there are more opinions on oil than religions or politics.

Reply to
SBC Usenet

Not really 5w30 has no bussiness in a older engine that has some wear in it because you will get lower oil pressure and reduced film strength too. They recoomand 5w30 for that last fraction of MPG in new engines,not because it protects it better in hot weather.

Reply to
SnoMan

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