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ED. What I was trying to say was that I doubt that the looseness of the baffle described could seriously raise the oil temperature at an amount as experienced. The increase of 70 degrees can't seriously be explained by loose baffles. I can say this with some knowledge because exactly the similar spot on the baffling was broken on my engine too. For a long time, because the mechanic did not see it and I did not see or understood the system either. Did I experience high oil temp readings up to 250 degrees?? Of course not. The main cooling action is done by the amount of air blowing through the engine cowling. To have a optimum effort on the Cylinders one does use the system of baffles. Although the cylinders are the hottest parts, there is the whole engine being heated up and dissipating heat. The whole thing with the upper and lower pressure is true in theory , but theres is the most important general low pressure produced by the side parts of the cowling. This is your main source of the low pressure area below your engine. With a C-75 engine one does not even need felt strips around the baffles because the engine produces normally not so much heat. The gap to the cowling is o.k. because it is a small gap and the amount of air going trough the cowling is immense , and I repeat here immense. So much, that there will be high pressure above the cylinders no matter what and low pressure afterwards. Just imagine this : If you remove all baffles from the engine , will all the cooling then suddenly stop when you fly? No, of course not. There will be still air go through all holes in the nose, streaming back out of the gaps at the side of the cowling. Will the air be less efficient cool the engine, you bet, but will it cool the engine at all ? Of course. The way the openings on the nose bowl are placed in regards to the placement of the engine is making sure that the air has to pass the engine, no matter what - cylinders first.. So I'd say with less efficient baffles one might see an increase of 10-20 degree at much. But please no temps around 250 out of the blue. I wonder what happened (with the engine) at the time when John could watch the temps rising.... I would guess broken rings or piston problems but the compression tests were fine.... Hartmut Ed Burkhead wrote: > Hartmut, > > I tentatively disagree that it doesn't matter too much about positioning of > the baffles. Though I'm not an expert on engine baffling, I've had baffling > faults pointed out to me along with discussions about how the ONLY air path > between the high pressure and low pressure areas should be the ones > intended. > > I'd say the baffling on the Coupe is pretty important to good cooling. > > John, > > I think you need to make sure there's some sort of sealing all the way > around the baffles so ALL the cooling air goes down the gaps through the > cylinder heads. > > Failure to have rubber or felt seals all the way around the outside of the > baffle (against the cowl) would let the majority of your cooling air get > away without cooling the cylinder head cooling fins. > > Ed Burkhead > http://edburkhead.home.insightbb.com/ > [EMAIL PROTECTED] > > -----Original Message----- > From: Hartmut [mailto:[EMAIL PROTECTED] > Sent: Tuesday, September 17, 2002 6:08 PM > To: Jack Lewis > Cc: John; [email protected] > Subject: Re: [COUPERS-FLYIN] Responses to overheating problem > > ----[Please read http://ercoupers.com/disclaimer.htm before following any > advice in this forum.]---- > > Jack is right . Fix the baffles. > > You don't need the strips on a C-75, but the baffles should be in the right > position. > > I doubt that the bent baffle would make so much effect that the temp goes up > to 250. > > The opening of the side cowl is creating a big amount of low pressure that > it almost does not matter > how effective the baffling is. > Air will stream. The only difference is how much air will be used directly > for cooling. > I think the temperature difference could only be some 10 to 20 degrees, > but not 70 degrees. > > Hartmut > > Jack Lewis wrote: > > > ----[Please read http://ercoupers.com/disclaimer.htm before following any > advice in this forum.]---- > > > > >Are the baffles that sensitive? > > > > Yes they are. Not only do they maintain high pressure air above the > > cyclinders, they also create a low pressure zone below the cyclinders. > > > > The whole system is just like your coupe gas tanks. The fuel will flow > into > > the one with less gas. When they are even, the fuel quits flowing. That > is > > probably what is happening to your engine. > > > > Air goes to the path of lest resistance. If resistance is equal the flow > > stops. > > > > Gaps in the system allows air to go over the top of the baffles, before it > > goes over the cylinder head. If it goes over top of the baffles the > bottom > > of the cowl becomes pressurized. When the bottom pressure goes up, it > takes > > more force to push the air over the cylinder heads. (You should always > have > > Positive pressure on top, Negative on bottom. This results in the air > going > > over the cylinders being forced from the top and pulled down from the > > bottom). > > > > There should be NO air entering the top of the engine that doesn't cool > the > > cylinders. > > > > There should be NO air entering the bottom of the cowl unless it has > cooled > > something getting there. > > In addition to fixing the baffles (it won't hurt even if it doesn't solve > > the problem), make sure that the seal around the air filter is also good > and > > the cowl fits snug in the front when closed. > > > > You don't have a lot of air to play with: > > There are two inlets for the air above the cylinders. > > One inlet for air below the cylinders (to cool the oil slump). > > The inlet for the slump cooling will about cancel one of the cylinder > > inlets. > > The air above the cylinder is also used for Carb Heat, Cabin Heat and > > Gen cooling. > > So you really don't have a lot of air to waste. > > > > Fix the baffles and tell us what happened. > > > > Jack > > > > ================================================================== > > TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm > > ================================================================== > TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm ================================================================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm
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