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195.6 OHV oil temperature and pressure...

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tomj View Drop Down
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    Posted: Aug/26/2016 at 4:21pm
i had some odd potential problems on my rally, that i suspected were temperature related, and today i got some very preliminary, non-scientific data that supports that... it's not like it's a wild theory that this engine has inadequate cooling -- it was introduced in 1941 as a 75 hp flathead, gussied up over the years to 135 hp, and mine is 150 hp, if i am very lucky. to say that the design and construction aren't up to today's task is not exactly sticking your neck out.

i know head cooling has problems, but those are easily fixed, and in my engine, nailed. 

oil is Mobil 1 15w50. first, my oil pressure at speed started dropping. i'm talking here about "highway speeds", where pump output exceeds the relief valve, so over say 2300 rpm oil pressure is maxed. i've been running 55 psi+ at highway speeds, and oil pressure varied from 50..52, then high 40's, then as low as 40, 41 psi... and i noticed that pressure tracked ambient temperature. 

oil pressure was much higher in the Sierra Nevadas and highway 50 through Nevada, and in Monterey and Santa Cruz (coastal), and lowest in (surprise!) Death Valley and north of Las Vegas.

engine coolant temperature was a solid 188 +/- 5 degrees -- meaning head temperature -- so that's not the issue.

when i got home i ordered two more temperature senders (i like the Stewart Warner gauge senders 280ED), one for oil and one for the lower block, and also a mechanical oil pressure gauge (to make sure my electric was not the problem!). the oil temp sensor screwed into one of the many main gallery cross-drill ports, toward the back of the engine. (the tip of the sensor protrudes into the gallery 1/8", and right over the cross-drill hole. i have a spare block in my shop that i checked it with.) the mechanical gauge went downstream of that.

the sensor intended for the lower block water jacket wouldn't fit... there's a 1/8 NPT hole between 2 and 3 on the "generator" side of the engine. the sensor fit in the test block, but there's a casting lump just inside that stops it on my engine. i'll work this out later. back to oil.

drove around locally and to no surprise, oil temp takes 20 minutes to come up to 150 degrees F. as expected. decided to run up the Glendale Freeway. exactly 10 miles up (mild incline) 10 miles back. i kept it at a steady 65..72 mph, not working hard. 80F ambient, coolant is 188F.

wow! engine temperature rocketed from barely 150F to over 230F, likely 240F. (SW gauges are non-linear, and 230 and 280 are close together). oil pressure dropped from 50's to 45 psi. upon return, a mile or two of surface streets, temperature dropped to under 230. it continued to drop slowly idling at home.

now 230F is not harmful, especially not to the synth oil. that's not the point here. if indeed oil pressure is viscosity-determined, this oil was a lot hotter than 230F during the rally. and viscosity control determines oil film and lubrication, and it's a safe bet that for even the "Power Pak" 135 HP, oiling is probably marginal.

my initial impression is, and i'll research this with better instrumentation and documentation over the next couple months, is that there is a lot of heat in the block and bottom end that has no way to escape except radiation of block heat into underhood airflow, and conduction through the cast iron to the head coolant.

i strongly suspect that oil overheating is another issue that hastens failure in these engines. i'm gonna continue to measure it for a while, and likely add an oil cooler and a temperature-controlled fan. i wish heat exchangers weren't so expensive, as i think that's a better solution, eg. warming up the oil too.

i'll find a way to measure lower block coolant, but i may instead just go ahead and plumb in forced circulation from head to block and back, to ensure good heat distribution and more reliable temperature measurement. lots or modern cars have coolant booster pumps for the heaters and one will be perfect for this.

i wonder what the 232 is like? safe to say it's better, whatever it is! anyone measured oil temperature on that thing?



Edited by tomj - Aug/26/2016 at 4:25pm
1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Aug/27/2016 at 4:55pm
Cooling the oil will help a lot. I've noticed a 5-10 psi drop in pressure on long trips back when I was driving a 196 all the time. I mean all day cruises at 70-75 when I could, with just gas/potty breaks and a longer lunch and/or dinner break. So that's like maybe 3-4 stretches of 3-4 hour runs with 10-15 minute breaks between the first and second, then a 45 minute or so break in the middle. In the summer the engine didn't really cool down much, what with heat soak during the short break. By the time temp stabilized I was off again. I did this a couple times a year for many years with no issues. That's one reason it used a bit more oil on a long run though, I'm sure. I don't think there is much you can do about the lower block cooling other than cool the oil. There are not water passages except around the cylinders, and they don't extend down very far. Maybe circulating more water there will help, I guess it has too, but cooling the oil will by far be the better solution.

You could make a water cooler/heat exchanger. Just solder a box around an oil cooler and pump in water. One of those circulation pumps could be used to pump it through a small radiator -- maybe another oil cooler serving as a radiator...
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Aug/28/2016 at 3:44am
In the early 1960's, my grandfather owned a 1960 Rambler with a 196 OHV that he would abuse out in the exact same stretches of California and Nevada desert as you described driving your Rambler through. And I mean abuse. He used to race people out there with it. I'm sure he had it close to or over 100 MPH on many occasions.

He didn't have any fancy synthetic oil either. He used Havoline 40W40 and was still running strong when he sold it in 1965.

If he couldn't blow up a 196, you won't be able to either.

It's possible to know too much about your engine. Having oil temperature and pressure gauges just gives you two more things to worry about. Just drive your car. Stop worrying about it. It's a tough little engine and can take it.




 


Edited by FSJunkie - Aug/28/2016 at 3:47am
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1977 Hornet
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Aug/28/2016 at 10:51am
I realize we're just driving cars, and if something goes wrong we can just pull to the side of the road.

But in the case of aircraft never try to tell a experienced pilot he can know too much about his engine, he uses his gauges, in particular that oil temperature gauge to keep him aware of his engine's current health, it's and HIS future depends on it.  A sudden, and unexpected engine failure can bring sudden death to a flier.
When I was in flight school I brought to the attention of my instructor the fact that the oil temp was slowly getting higher, and the oil pressure was slowly going down, while the cylinder heat temp was constant.  We turned around, cut the session and returned.   At the base the oil analysis showed bearing material in the oil,  on engine disassembly , one rod bearing was going.  All that brought to our attention to what the gauges were reading, if we had ignored the gauges we might have lost the engine on that flight, or the next student might have.

  But a sudden and unexpected engine failure in a car can be more trouble than just pulling to the side of the road.  There's the great expense of towing, getting in touch with help, not everywhere is this country has cellphone coverage, there are places you don't want to spend much time with a broke car.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote vinny Quote  Post ReplyReply Direct Link To This Post Posted: Aug/28/2016 at 12:59pm
I got quite a few years on my 196 as a daily driver and at 120k miles took it apart for a refresh. The machine shop could only find -.002 bearings but said they would be too tight and elected to go with the originals. I was surprised to see the grey Babbitt material still intact because every engine I had previously taken apart at that mileage, the bearing material  had always been worn off to the copper.

Although these engines may have been a little short on power I think as they came out of the factory they were as reliable as any and once up to speed on the highway they were actually not bad at all.

Second go around at 145k miles I found a lot of what looked like black bits of carbon covering the oil pickup screen. I have to admit I didn't investigate enough to find the source but I didn't think it was the umbrella seals as they looked intact and I had replaced them when the head was done previously. With that huge oil drain plug and paying closer attention at oil change time I probably would have noticed that. I don't remember having a problem with the oil light coming on but starvation was occurring.

Close monitoring of temperature and oil pressure would certainly help in detecting and rectifying potential problems as they occur.








Edited by vinny - Aug/29/2016 at 7:11am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/29/2016 at 12:48am
time for a teardown. last couple of days, upon cold start (overnight park) a VERY LOUD metal to metal clatter/rap until oil comes up, and since the rally, a rap at "high rpm" eg. right before an upshift...

a voluntary teardown now will be relatively painless and inexpensive. compared to disaster recovery.

yeah, i wont fall out of the sky and die, but breakdowns far from home are very expensive. if i had a 350 chebby it would be different, but ain't anyone out on the road gonna have a motor for me.

i will probably add more 1/8" NPT holes for more temperature sensors, including a bung in the side of the oil pan. they cost nothing. the engine's only 6 years old, 40K miles, but half of them were hard driving, and all my cooling system experiments. i'll document the teardown and wear. it's put up or shutup time.

oh and in 2011 or 2012 i sheared the oil pump shaft coming home from the AMCRC meet in in Sacramento. the cause was my "improvements" to the oil pump... it was very hot out, i was at a rest stop S. of Stockton i think, pulled out onto the freeway, saw the scary RED LIGHT, cut the engine... $1200 tow home. that's when i started doing oil analysis. it's been OK, lead slightly high, but who knows... it is almost certain that that event the oil was very hot as well, like the rally. it was Mobil 1 then also so the oil survives, but it seems plausible i stressed bearings then.


1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Aug/29/2016 at 5:38am
I thought the same thing when I filled my oil pan with water. That was in a high mileage engine too. No harm done. But if you have a knock somewhere something is loose! Since you can get the oil pan off in those cars without too much work you could just drop it and inspect the bottom end. I bet you have a rod bearing giving up...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/29/2016 at 3:56pm
yeah, something is wrong. it's parked and i'm going to yank it, starting this week.

the oil pressure thing is weird. it didn't just drop across the board. 

before, it ran 15 psi at idle, increased to 55 psi around 2300, 2400 and peaked there. hot.

after, idle is 25 - 30 psi, increases to 45 psi around 2300, 2400, peaks there. hot also.

i can see how chewing lead out of bearings could drop high rpm oil pressure, but wtf would increase it at low speeds? that's why i got a second pressure gauge to check. it agrees.

assuming it's not filled with metal bits, probably i'm ok... then head, cam, lifters should be fine. i hope i just ate the lead off the surfaces and can get away with turn crank journals, new bearings, etc. probably replace timing chain i suppose. i want to get it apart ASAP to know what is what. i have another rally in early October i wanna do!

oil's off for analysis. as far as i'm concerned, you can't have too much data. if my proposed fixes work (oil cooler, block circulation) then fine, if not, i'll know to slow down -- and plan the next engine, which will be a 232. if i can't run this engine hard, that's that. but i think i can...


1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Aug/29/2016 at 6:25pm
Of course you need to check the oil pump, since you made mods. Something could have clogged the filter, which might raise oil pressure at idle. Might want to cut the one one the car open...
Did you leave the block mounted oil pressure relief valve operable?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/29/2016 at 8:19pm
oh yeah, oil pressure relief is in place and working. the pump is stock, restored so after the mods i'd made. and yeah, i will cut that one open and look at the oil for sparkly glitter.

the sample i sent off was taken from the dipstick tube immediately after a 20 minute drive. though i only took a few ounces there was no obvious metal in the oil.

(unlike Jim (squirrel)'s Edsel, during the LeMons Rally, which decided to crunch down on some very hard parts (rollers or balls) in the OD transmission. apparently it made a series of CRUNCH-BANG! sounds, at 70 mph on highway 50... they changed gear oil in Ely NV in a parking lot, and ooh! pretty! OOPS DAMMIT. swirly glitter in the oil. 1000 miles later it started groaning... though they got home OK. i hope i see nothing like that in the pan.)

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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