Why does my 5.0 Engine run Hot?

Pat,

I'm not a 5.0 expert, but it sounds like the gague is right in the middle of the "normal" range. In fact, when my mom owned a '77 LTD II, the needle sat right over the R, so that the temperature gague read "N O M A L", which I found very funny when I was taking Spanish in high school.

The oil does provide cooling, so if you're actually getting low oil pressure at warm idle (and not a faulty reading from the gauge/sender) that could result in higher temperatures than you saw before

I have a hard time imagining that you could bend the pickup tube without hitting the pan hard enough to put a big dent/hole in it, but stranger things have happend, and there will probably be someone in the NG that had it happen to them. Whatever is going on, I'd want a good mechanic to take a look at it. Whether it's a bent pickup or a pump starting to go south (and the symptoms sound to me like it's a pump that's got clearances larger than they should be), low oil pressure is not something I'd just let go. If it is just a bad sending unit, so much the better.

take care, Scott

How many miles are on the car?? How long have you owned this ride??

I'd service the motor and use a quality oil filter like a Motorcraft. If you have access to a mechanical oil pressure gauge Id manually check the oil pressure problem.

Does this 90 has a clutch fan system? If it does Id check the check, if not make sure the fans are coming on if electrical fans. If all that checks out look at the cluster regulator, sending units and gauges.

Good luck

David

First off, that range of the gauge say's "Normal" for a reason. It's normal. Leave it alone. Stop wasting money on parts you don't need. Second, hot oil pressure drops because bearing clearances increase. Remember that hot metal shrinks, so clearances increase. Oil starvation will increase bearing wear. A bad pick up tube will decrease pressure at high rpm's, not low. Try switching to a higher grade of oil, like 10W-40, or 15W-50. Years ago I was driving my father's old Dodge van. He was in the construction business, and abused his vans regulalrly. I noticed the same thing - the pressure light would flicker when at a stop light. I told him about it, and told him how to fix it (heavier oil), and why he should fix it. So about a month later I was driving his van again, and the flickering had stoppped. I asked what he did and he replied, "Oh, I just reached up there and removed the bulb".

Actually, metal expands when heated. The oil pressure fall-off is due to viscosity changes, and is normal.

-JD

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Also, isn't the oil gauge activated by only an on/off sending unit switch?

Not everyone has an 'idiot guage' installed. I plan to convert mine over this winter to the older style that actually indicates actual oil pressure.

-JD

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Whoa. Why the hostility? Since the temp gauge was stock why is it unreasonable to assume that the oil gauge was changed?

No hostility was intended i think..it really is called an idiot gauge.

Matt

Correct, that's a common term for that style gauge.

The 1990 5.0 had a real oil pressure gauge though. These gauges can be all over the scale. It's the 2.3L that comes with the idiot gauge. It goes up to about half whenever the pressure reaches a certain point, and then falls to 0 if the pressure falls under that point. Unfortunately, by then, it's usually too late in those cars.

JS

No hostility intended; 'idiot guage' is an actual term for these.

The oil pressure guages on 96-on Mustangs were converted over to the 'idiot guage' type of display, which indicates a warm, fuzzy 'in the middle sorta normal' thing, which is actually a predetermined, fixed position, designed to keep from frightening Mustang owners who might otherwise begin convulsing when they see the actual oil pressure fluctuate.

I think it was a silly idea to change from what was otherwise a useful guage. I plan to convert mine back to something that actually functions properly...someday.

-JD

_________________________________ JD's Locally-Famous Mustang Page: http://207.13.104.8/users/jdadams Please note: UCE is deleted at the ISP server level. Unless your address is on my 'accept list', your mail will never reach me. See my website for more information.

The '94 also had an "idiot gauge". But I was wondering though what real value is there in knowing the actual "oil pressure". If there is a reason the only one I can think of would be an early warning to the extent that a gradual decrease in pressure is an indication of impending disaster. Total loss of pressure and be seen on both types of gauge.