There is a plunger and spring that is removed if a Vernatherm is added. On engines with the stock Lycoming oil filter adapter they don't interfere with one another so you can reinstall the spring and plunger and send all the oil through the cooler all the time. Check out this thread: http://www.vansairforce.com/community/showthread.php?t=45548&highlight=vernatherm
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High oil temps
- Thread starter Timberwolf
- Start date
Timberwolf
Well Known Member
Mike,
Thanks for the link. I saw that before, though I haven't looked as close as I should, I glossed over it because I thought the top part where is saying to insert the spring and plunger is where my oil temp sensor is located. I'll look again when able.
Thanks for the link. I saw that before, though I haven't looked as close as I should, I glossed over it because I thought the top part where is saying to insert the spring and plunger is where my oil temp sensor is located. I'll look again when able.
Reformed SeaSnake
Active Member
You should not need to do that. The only reason the Vernatherm would be the problem is if the plunger is failing to seat completely due to scoring e.g. You mentioned that you have squirters and a normal operating pressure of 90-95 psi. As has been mentioned in this thread, a higher set point on the oil pressure bypass valve leads to a greater proportion of the pumped oil going to the engine (vs getting bypassed back to the sump). With the squirters that will lead to higher oil temps. Adjusting the bypass pressure to lower the normal operating pressure will lower the oil temperature but it will also reduce the piston cooling being provided by the squirters as less oil will be sent to them.
If it were me, I would fix the airflow issues first; switch out the 3" scat for 4" and balance the airflow to the cylinders so that #4 is not getting so much of the cooling air. Once you do that, if you find the oil temp is still a bit high and you don't mind increasing the CHTs, you could lower the oil pressure bypass valve setting. That will reduce the cooling load on the oil system and raise the CHTs a bit.
Of course, remember the advice is free and probably worth every penny
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erich weaver
Well Known Member
There is one additional factor to consider as well. Higher oil pressure has been recommended by some as a way to achieve additional lubrication of the camshaft, which has been identified as somewhat deficient in Lycoming engines and their clones.
erich
erich
Oil gets to the cam lobes by being thrown off the crank via centrifigal force, and very little bleed oil from the lifters due to the horizontal orientation. I'm not sure that additional flow will fundamentally increase the amount of oil getting to the cam as it is likely pretty significant at higher RPMs'
I don't think that the lycomings have a problem with cam lubrication at higher RPMs. I would speculate that they are deficient at startup and lower RPMs, but increasing the oil pressure relief won't help at 1000 RPMs (you need more centrifigul force, not more oil flow). Further, I haven't read about a lot of cam failures or lobe wear that didn't also include spalling. Others in the overhaul business could better identify the quantity of failed lobes that weren't spalled. Lobe failure with spalling is due to corrosion and initial start wear. Neither of those can be addressed through increased oil pressure.
Larry
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Oil Pressure
Increased oil pressure is for VALVE lubrication not CAMSHAFT. The higher oil pressure has been used for years in new production Cessnas, ever since the restart of single production. The oil pressure gauge reads the same but the pressure is approximately 10# higher because the oil pressure line goes to the front of the gallery.
Aerobatic airplanes also benefit from higher oil pressure. There are certain maneuvers where there is a significant drop in oil pressure with the Christen or similar inverted oil systems. With the higher oil pressure setting the pressure drop will be of slightly less duration.
For camshaft lubrication at one time there was an approved modification to the Lycoming cam to create an oil hole at each lobe to provide pressure lubrication to the lobe/lifter interface. This never became very popular, partially because of the increased use of roller lifters.
Increased oil pressure is for VALVE lubrication not CAMSHAFT. The higher oil pressure has been used for years in new production Cessnas, ever since the restart of single production. The oil pressure gauge reads the same but the pressure is approximately 10# higher because the oil pressure line goes to the front of the gallery.
Aerobatic airplanes also benefit from higher oil pressure. There are certain maneuvers where there is a significant drop in oil pressure with the Christen or similar inverted oil systems. With the higher oil pressure setting the pressure drop will be of slightly less duration.
For camshaft lubrication at one time there was an approved modification to the Lycoming cam to create an oil hole at each lobe to provide pressure lubrication to the lobe/lifter interface. This never became very popular, partially because of the increased use of roller lifters.
Timberwolf
Well Known Member
Trip to SNF was a non event with oil temps leveling off at 190-200 at cruise. I have the 4" scat and will get started on that ASAP. The bigger thing that worried me was the CHT's. They are very unbalanced from side to side. cyls 1 and 3 were 316, 325, but cyl 2 was 280 and 4 was down to 243.
So, what's the proper way to push air over from the left side of the cowl? That way I can also divert more to the cooler scat. I would like to get it down to a single 9 row cooler and take off the 7 row to avoid the plumbing and complexity. I will also be fabbing up some of the cowl ramps for the top cowl while I'm in there.
So, what's the proper way to push air over from the left side of the cowl? That way I can also divert more to the cooler scat. I would like to get it down to a single 9 row cooler and take off the 7 row to avoid the plumbing and complexity. I will also be fabbing up some of the cowl ramps for the top cowl while I'm in there.
Check the basics -
Have you thoroughly examined the baffling on the bottom of the cylinders? Are the wrap-arounds on the bottom tight against the fins? Is the bottom plate that covers between cyl 2 and 4 in place? Is the crankcase sealed properly with RTV in those hard to reach areas? (This thread seemed to start with a mention of some inadequate or improperly configured areas. Just asking.) All the high level discussion about air mass, oil flow and SCAT diameter, might be worth confirming the left side of the engine is properly baffled everywhere.
Have you thoroughly examined the baffling on the bottom of the cylinders? Are the wrap-arounds on the bottom tight against the fins? Is the bottom plate that covers between cyl 2 and 4 in place? Is the crankcase sealed properly with RTV in those hard to reach areas? (This thread seemed to start with a mention of some inadequate or improperly configured areas. Just asking.) All the high level discussion about air mass, oil flow and SCAT diameter, might be worth confirming the left side of the engine is properly baffled everywhere.
Timberwolf
Well Known Member
Gary, all of the baffling is tight and well sealed all the way around now. The left 2 cylinders are too cool and the right ones are just about right. Just seeing if anyone has made a dam to direct air over towards the passenger side.
I have the 4" scat tube, but need to make up the flange for the scat from the cylinder baffling and also fab up a new flange for the cooler. In the mean time just thinking of ideas that may be causing the uneven airflow in the cowling. The oil cooler behind the #4 cylinder didn't raise the temp on it at all as I figured it would. It almost seems like the opposite like it's drawing more air across the cylinder on the way to the cooler.
I have the 4" scat tube, but need to make up the flange for the scat from the cylinder baffling and also fab up a new flange for the cooler. In the mean time just thinking of ideas that may be causing the uneven airflow in the cowling. The oil cooler behind the #4 cylinder didn't raise the temp on it at all as I figured it would. It almost seems like the opposite like it's drawing more air across the cylinder on the way to the cooler.
Timberwolf
Well Known Member
Just thinking out loud here, but what is the possibility injector #4 is flowing way more fuel? Whether it was put in on purpose to help provide more fuel to make up for lack of cooling with the oil cooler mounted on the back side, or it's just a heavy flowing injector? EGT's on the other cylinders will peak at 1415 or so while #4 remains in the 1200's. I'll work the oil cooler issue then work with Gami to get them all balanced as that was the plan in the first place.
Does #4 also peak around 1415? If so and it is running in the low 1200's, it is very rich or very lean. More so than would be expected by normal out of the box injector imbalance. Please verify where and when it is peaking, relative to the others. You could have a different issue in that cylinder that is preventing it from producing full power, such as a leaking valve or many other things.
Larry
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