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- Joined
- Aug 6, 2007
- Messages
- 5,331
- State - Country
- GA - USA
- Vehicle Year
- 1999
- Vehicle
- Ford Ranger
- Engine
- 5.0
- Transmission
- Automatic
- Total Drop
- few inches
- Tire Size
- ~30"
99 Ford Ranger, 4.0L OHV, Auto Trans, 4wd. Little over 3000 miles since engine rebuild. Last oil change less than 1000 miles ago. 5w30 since rebuild.
Issue: With engine up to temp (after driving for a while), occasionally when I stop with truck in drive and idling with my foot on brake the oil pressure gauge goes crazy dropping to low pressure. Apply slight pressure to throttle it returns to normal, put in park while still idling and not touching brake or gas pedal it returns to normal. Never moves while driving.
Started after replacing radiator last week. Driven about 80 miles since replacing radiator. First drive was about 60 miles to work and back (30 miles each way), and problem appeared when pulling into my drive way. Other drive was about 20 mile round trip to grocery store, and check checking for repeat issue. Had small trans cooler leak that is fixed, fluid levels still good.
So I can only think of a few possibilities. A) bad sender B) idle speed too low C) Oil too thin
Although the OE style senders on these are crap switches, I don't really buy it as being the issue. If sender were bad I aught to see oil pressure irregularities more often than I do.
Low idle speed could be an issue I suspect. I know oil pressure is dependent on engine speed. If engine speed drops too low at idle it could be dropping the oil pressure just low enough that it isn't enough for the sender at idle. That said I do not hear, see, or feel anything unusual for the truck at idle when the is happens, excluding the crazy gauge of course. I have an engine tune on it that could have the idle rpm set too low. I put the tune in just before a trip in August, which was the last the truck was driven before replacing radiator, and I was limping it home thanks to the radiator. I didn't allow the truck a chance to run hot, so heads and gaskets should not be an issue (if they are I'm grabbing a match and gas can).
Too thin of oil. 5w30 just seems awful thin for one of these motors. It's tolerances are a lot bigger than anything built now that requires 5w30. That's the grade everything seems to list for it, and since it's a new motor, so that's what I put in it. Didn't have any issues with 5w30 prior to oil change, but may be coupled with that low RPM deal.
My next step will be to put it back on stock tune, and test it again. Any other suggestions as to what could cause this?
Issue: With engine up to temp (after driving for a while), occasionally when I stop with truck in drive and idling with my foot on brake the oil pressure gauge goes crazy dropping to low pressure. Apply slight pressure to throttle it returns to normal, put in park while still idling and not touching brake or gas pedal it returns to normal. Never moves while driving.
Started after replacing radiator last week. Driven about 80 miles since replacing radiator. First drive was about 60 miles to work and back (30 miles each way), and problem appeared when pulling into my drive way. Other drive was about 20 mile round trip to grocery store, and check checking for repeat issue. Had small trans cooler leak that is fixed, fluid levels still good.
So I can only think of a few possibilities. A) bad sender B) idle speed too low C) Oil too thin
Although the OE style senders on these are crap switches, I don't really buy it as being the issue. If sender were bad I aught to see oil pressure irregularities more often than I do.
Low idle speed could be an issue I suspect. I know oil pressure is dependent on engine speed. If engine speed drops too low at idle it could be dropping the oil pressure just low enough that it isn't enough for the sender at idle. That said I do not hear, see, or feel anything unusual for the truck at idle when the is happens, excluding the crazy gauge of course. I have an engine tune on it that could have the idle rpm set too low. I put the tune in just before a trip in August, which was the last the truck was driven before replacing radiator, and I was limping it home thanks to the radiator. I didn't allow the truck a chance to run hot, so heads and gaskets should not be an issue (if they are I'm grabbing a match and gas can).
Too thin of oil. 5w30 just seems awful thin for one of these motors. It's tolerances are a lot bigger than anything built now that requires 5w30. That's the grade everything seems to list for it, and since it's a new motor, so that's what I put in it. Didn't have any issues with 5w30 prior to oil change, but may be coupled with that low RPM deal.
My next step will be to put it back on stock tune, and test it again. Any other suggestions as to what could cause this?
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