Back on topic..anyone's thoughts on the "stock" factory oil cooler adapter, with the parallel plumbed cooler? I guess we could put in a cooler pretty cheap, and see if it drops oil pressure at all. If it does, it'll be easy enough to swap back to no-cooler. Since it'd be parallel, 3/8" lines would be fine.
OK, now there's real weirdness afoot...
I installed the auxiliary radiator (a heater core from a Volvo 122, of which I have aplenty) and started the 460 to check temps. The heater core got uniformly warm, temps hovered around 180 to 190, no leaks, so I assumed everything was fine...
Now, I decided to try something different. I adjusted the idle speed up from about 1000RPM to about 1500 RPM. Slowly, the temp gauge climbed, up to about 205 or so, and then dropped back down to 185. It kept doing this. Oil pressure stayed about 50 psi.
Next I adjusted the idle up to 2000RPM. Now the temp gauge started really going up, it got up to around 230, and I was afraid I was going to have to turn the idle down, but then it dropped- back to about 190 or so.
Now I am really confused. Is the themostat (a 180 degree stat) that wonky? I do have (4) 1/4" holes drilled in it- is that flow just trivial?
At this point I'm thinking about going with one of those t-stat plates, with a 1" hole or so. Either the stat is just not responding quickly enough at those higher RPMs and heat loads, or possibly there's an air pocket moving its way around the engine.
Any thoughts?
You have a sticky thermostat, put a new one in it.
Just curious - why are (were?) you opposed to running no thermostat?
Can you confirm that the temp gauge is accurate?
ProDarwin wrote: Just curious - why are (were?) you opposed to running no thermostat?
Not opposed to running a restrictor plate, I just don't want to run with nothing there at all. My understanding is the thermostat's other, secondary job is to act as a flow regulator, so that too much water doesn't go through, thus limiting the heat transfer of the water. Though I am beginning to question that assumption.
Pretty sure the temp gauge is accurate, at low RPMs it sits there oscillating between 180 and 190, roughly, corresponding to the t-stat opening and closing. I do need to get some batteries for my heat gun, and check the temp at the upper radiator hose, just to be sure though.
Running with out a stat can cause overheating. we found that out when racing the Ford flat head.
I was thinking. Those holes in your present stat might exacerbate the problem making it difficult for the thermostat to control the temperature by bypassing some of the coolant.
volvoclearinghouse wrote:ProDarwin wrote: Just curious - why are (were?) you opposed to running no thermostat?Not opposed to running a restrictor plate, I just don't want to run with nothing there at all. My understanding is the thermostat's other, secondary job is to act as a flow regulator, so that too much water doesn't go through, thus limiting the heat transfer of the water.
As a mechanical engineer, this doesn't make sense to me. What's the hypothetical scenario with infinite water flow? All of the water is exactly the same temp. The equalized value somewhere between engine temp and radiator temp. The only way for it to overheat would be too high of an ambient temp or not enough cooling area.
ProDarwin wrote:volvoclearinghouse wrote:As a mechanical engineer, this doesn't make sense to me. What's the hypothetical scenario with infinite water flow? All of the water is exactly the same temp. The equalized value somewhere between engine temp and radiator temp. The only way for it to overheat would be too high of an ambient temp or not enough cooling area.ProDarwin wrote: Just curious - why are (were?) you opposed to running no thermostat?Not opposed to running a restrictor plate, I just don't want to run with nothing there at all. My understanding is the thermostat's other, secondary job is to act as a flow regulator, so that too much water doesn't go through, thus limiting the heat transfer of the water.
Yes, I know, I'm an engineer too. The explanation I have heard is that if the water flows too quickly through the engine, it doesn't have time to absorb the heat, and the water stays cool, but the engine gets hot. Or something like that.
But this has always been unsatisfying to me. It would seem like in the analogy of a forced convection in air, the faster you move the air, the cooler the object you are cooling gets. The only way I could see this breaking down is if there's some fundamental difference in heat transfer between liquids and gasses, which there may well be. Fluid mechanics was never my strong suit.
In reply to ProDarwin:
Something to with the fluid moving too fast, I'm not sure if cavitation is the right word, but something to that effect occurs. Don't forget that this engine's water jacket design predates computer aided engineering and was purely trial and error guess work until it worked good enough.
Ordered a new radiator cap (13 psi) and a set of the Moroso thermostat restrictor discs. They're like $6 for a set of three. I'll drop the largest one in and see how it handles the 2000 RPM test.
ProDarwin wrote:volvoclearinghouse wrote:As a mechanical engineer, this doesn't make sense to me. What's the hypothetical scenario with infinite water flow? All of the water is exactly the same temp. The equalized value somewhere between engine temp and radiator temp. The only way for it to overheat would be too high of an ambient temp or not enough cooling area.ProDarwin wrote: Just curious - why are (were?) you opposed to running no thermostat?Not opposed to running a restrictor plate, I just don't want to run with nothing there at all. My understanding is the thermostat's other, secondary job is to act as a flow regulator, so that too much water doesn't go through, thus limiting the heat transfer of the water.
This always intrigued me as well. If the water is moving at 100 gph (round numbers) with a stat, each gallon of coolant picks up 50 units of heat from the block and sheds 50 units of heat in the radiator. If you remove the stat and its flowing 200 gph, each gallon picks up 25 units of heat and sheds 25 units of heat, but its doing it twice as often.
With slower coolant speeds, the temperature differential between the radiator and block would be larger, and as coolant flow increases the temperatures would be closer together... but the net amount of heat being transferred shouldn't change regardless of the flow rate. It either picks up 50/sheds 50 or picks up 25/sheds 25. The net result is heat in = heat out which means steady temperature.
Of course, in your case, Volvo, the temperatures are rising which means heat in > heat out for an unidentified reason.
I know this is a tangent, but I'm curious as to the physics behind this as it might help with this 460. Provided the coolant is moving fast enough that it doesn't absorb too much heat (and boil) before moving to the radiator, why would it matter how fast its going?
In reply to curtis73:
I wouldn't mind a little discussion on this myself. There seems to be a lot of debate about it. I've seen cars run cool with no t-stat, and I've also experienced engines (like the 351M/400 Ford, for example) that absolutely require the thermostat to not overheat, due to the design of the cooling system.
I do know that when it comes to heat transfer and heat vs temperature, things are not necessarily linear. You get into turbulence, navier-stokes effects, and other neat things. But yes, for the current problem, as RPMs rise, heat in > heat out, at least until temperature finds its new, higher equilibrium. Keep in mind we're running straight water here, although with the radiator pressurized the BP will be higher than 212F. At 13 psig, for example, the BP would be around 240F.
http://www.engineeringtoolbox.com/boiling-point-water-d_926.html
Cavitation could be a concern with high flow rates in passages that aren't smooth. A little back pressure might be necessary to keep the passages 100% full.
I'm also thinking you have a sticky thermostat. Cavitation shouldn't be happening at 2krpm. I bet that before the temperature starts to drop, the (non-thermostatic) aux. cooler gets extra hot, right?
If you are having cavitation, you can increase cooling system pressure with a higher-pressure cap to reduce it, but then you have to watch for new leaks everywhere.
GameboyRMH wrote: I'm also thinking you have a sticky thermostat. Cavitation shouldn't be happening at 2krpm. I bet that before the temperature starts to drop, the aux. cooler gets extra hot, right? If you are having cavitation, you can increase cooling system pressure with a higher-pressure cap to reduce it, but then you have to watch for new leaks everywhere.
The cap right now is marked something like 14-18 psi. Honestly, it worries me a bit- that's awfully high pressures for this old of a system. I ordered a new, 13 psi cap.
Will be very interesting to see what the t-stat replacer discs do.
In the meantime- I cut these cool hood cooling vents. They also double as handy hood-lifting handles.
At that pressure you can probably rule out cavitation ever being a problem, considering the engine stays under 4krpm. If you still have cooling problems with a large restrictor disc or a thermostat-less setup, then it might indeed have a blockage somewhere.
Well folks, I think knock on wood I might have it licked!
The package from Summit arrived today and I could barely contain my enthusiasm.
In a few minutes I had the thermostat yanked out and the largest of the three plates (1" hole) installed. (the other options were 3/4" and 5/8").
After topping off the radiator and installing the new cap,
I let the engine idle for awhile at 1100 RPM. It got up to about 175 degrees and stayed there. Then I did the "2kRPM" test- turned the idle up to 2000 and let it "soak". The temperature crept up a little, to about 185. AND THEN- because the car was sitting still, I turned on the electric auxiliary fan mounted in front of the radiator. The temps edged back down to about 175 or so, and stayed there. When I shut the fan off, they went back up to 185. This seems like a pretty good indicator that when the car is actually moving, airflow will help keep the temps where they need to be.
Oh, I did discover one thing while I was playing with the car- the exhaust manifold bolts were loose. Apparently the heat cycling loosened them after we installed the manifolds a few weeks ago. I could actually see little spurts of flame coming from the heads through the little slit between the manifold and the heads. So I retorqued them- which quieted the engine down some. :-)
I backed the car down the driveway all the way to the road and tried a little 60 foot drag run. Throttle response was..impressive. It revs very willingly, amazing for such a behemoth. It has a real bark to it, I'm not gonna lie, it sounds amazing. :-)
In commemoration of this minor victory:
NICE WORK!
That gauge cluster is MINT
tuna55 wrote: NICE WORK! That gauge cluster is MINT
Thanks. I got my inspiration from the gauge cluster in this car:
See the resemblance?
poundsign nailedit
You could open up those hood vents a lot more if you wanted to. Also putting a little lip/ramp on the leading edge will help draw air out.
You'll need to log in to post.
