Running a little hot

[lady lindy]

Can anyone give me a clue as to why my 7AC would be running somewhat hot - about 35 or so degrees hotter on the oil temp, along with a lower than normal pressure reading, about 5 under normal. The first time up after an annual is when this appeared, so I know it isn't a clogged screen. All suggestions????? THANKS!

[rkittine]

I have had some similar problems in the past with the impeller in the oil pickup. It was worn and if the plane sat for a long time, the oil pressure would be low causing an increase in temperature. With more frequent running of the engine, it cleared itself.

[MikeB]

What engine and how hot is hotter?? Or maybe I should ask what was the normal oil temperature and pressure before the problem?

MikeB

[lady lindy]

Thanks for your replies. That's a helpful suggestion, Robert. The Champ did sit for quite awhile in the shop - a couple months, because the mechanic got a long-lasting flu, then fell and hurt his back before he could really get going on the annual. Plus I had taken some shoulder harness/seat belts to be installed, too. So that could be it, sure hope so.

And, Mike, sorry I wasn't more specific. It's the 65 Continental, normally runs at about 140 on the temp on a day like yesterday, with 40 on the pressure (starts out there, drops to a little above 35 as it heats up). Yesterday it was at 185 on the temp and started out at 35 on pressure, dropping to about 30.

[MikeB]

I also have a 65 in a Champ in addition to a L16 with a 0200. Anyway, 185 is a little high for a 65. They're pretty cold blooded unless the ambient temperature is up as they don't burn a lot of fuel so they don't generate a lot heat either. The fact that your pressure is down with the oil temperature up makes me believe it's not the temperature gauge but I guess testing the gauge would be a good first step. I'd pull the screen anyway and check for metal just to be sure you're not losing a bearing (and put your mind at ease). Engine baffling out of place also comes to mind especially after an annual and epecially if the seal between the cowl cover and the rear baffle has been disturbed, but look at all the baffles and seals. Clogged pickup tube screen is another possibility or a bit of debris in relief valve but I'm willing to bet if you can get the oil temperature down the pressure will increase back to normal. 30 psi is on the low side of normal but my 65 has only carried 28 or so if the temperature is up around 170 during the summer.

As Robert mentioned A65's are notorious for losing their prime after sitting as the pump housing,gears and end plates wear but I'm not sure why the oil temperature and pressure would clear itself after a period of operation but stranger things have happened, I guess.

MikeB

[lady lindy]

Thanks, Mike, for all the suggestions, I will check them out. I talked to the mechanic last night, and he assured me the screen was fine when he removed it during the annual, that it just had a little carbon in it. But, yes, checking it again would put my mind at ease. Thanks so much for your great input!

[lady lindy]

Well, it finally quit raining long enough for me to take the Champ up, and the high oil temp/low pressure problem remains. I flew for almost an hour, and the oil temp was a couple degrees down from the other day (it was 183 instead of 185), and the oil psi a degree or two higher (just barely under 30 as opposed to 28), but essentially the same. Both are under "redline", but it's not normal for my Champ. There is a piece of baffle missing just about the middle point at the back of the engine, so I'm going to see about getting that fixed first. I think I'll also pursue Mike's suggestions before going up again.

What kind of normal oil temps/pressures do you other Champ drivers have with 65 hp Continentals? My oil temp has always been around 170 or a little higher on a really hot day, with the pressure (once heated up) around 35 psi or a little less.

[MikeB]

The (normal) oil pressure as you described it is about 'normal' for a 65 horse at 2100 rpm. The regulator spring is set for about 35 psi. It will usually run up to around 40 or so when it's cold and then settle down once the oil temperature is up. 65's run slower than 85's (for example) so you really can't compare the two......pressure wise as more rpm usually amounts to more pressure. The missing piece of baffle can and will affect engine cooling and temperature. I'd certainly get it fixed. Also, check to make sure the baffle seals are tight to the cowling and they are facing forward so the incoming air flow makes a seal. It's a 'pressure cowl' so it needs good sealing to work properly.

Regarding oil pressure: (I've posted this several times before) most of these old engine blocks have worn cam shaft bores in the alumium housings as they don't have actual replacable cam bearings so they tend to lose oil pressure from excessive cam to bore clearances for oil to leak by. However even 25 psi seems to be sufficent to keep things lubricated and the oil pressure gauge pickup point is at the very end of the oil flow just before the regulator assembly so it would tend to run a bit lower there anyway (my opinion). I suspect if it would be possible to check the oil pressure on the left side of the block it would run somewhat higher.

As I posted above my 65 runs about 28 psi at 2100 rpm and 170 degrees.

MikeB

[joea]

Like Mike says, the temps you are having are pretty normal.

If you do have a section of baffle missing, especially in the back of the engine, that really needs to be fixed. The back baffling is the high pressure point in the cowling and if the incoming air goes out the hole, its not going over the hot cylinders and your oil temps will be higher. Higher oil temps results in thinner oil and thus lower oil pressure.

What part of NW Mo are you located in? Was just in St. Jo...

Joe A