Hello everyone,
I usually let my 87 Turbo-T idle for two minutes or so before shutting it down if the turbo has spooled up before I reach home, as is customary on turbocharged aircraft such as the PA31 navajo, where the engines must run for 3 minutes after touchdown to avoid having oil stop lubricating the turbo bearing. Recently though, one of my friends told me modern cars had "turbo brakes" which stop the turbo when the car is shut down. This led me to wonder if I was just wasting gas when I was letting my TR idle before. Could anyone please clear this up?
Thanks in advance,
Jason
87 Turbo-T
92 LeSabre
Sounds like your friend needs to put the crack pipe down... The turbo impeller will spin until it stops.
HTH,
Ron
forgot to add that you are not wasting gas in my opinion by letting the car run for a min or two after stopping. It helps cool the oil flowing to the turbo bearings. I usually wait 1-2 mins before shut down myself after it get home.
Ron
Jason ask your buddy when you should change the pads in the turbo brakes, and also how do you bleed them? Just say no to crack!
Please allow me to rephrase my question: Is the turbo a wet bearing or is it lubricated only when there is positive oil pressure. Thanks for your help.
Jason
Sorry for the hazing, I couldnt help myself. OK when the car is running positive oil pressure sends oil thru the oil feed line and lubes the shaft. When the car is shut down the oil pressure stops and no longer lubes the shaft. The reason for leaving the car idle for a minute or two is so some of the very hot oil can be circulated out of the oil feed line. If you constantly shut down car abruptly after parking over time the hot oil left in the feed line will cake up and possibly clog this line. I currently run an HKS turbo timer in my TR, basically when wired up correctly this unit will keep the car running for an adjustable preset time after you take the key out of the ignition. So you dontreally have to sit there and wait. Hope this helps just my 2 cents.
Prolonged idle shut down is normally not necessary. Unlike aircraft that are under a lot of power when landing our cars go thru a residential area before coming to the driveway. During this time the oil temp and turbo get a chance to cool down. True if you are on the interstate and see a gas station off the exit ramp you should let it idle before shut down. Under normal driving conditions this is generally not necessary. I had a customer with over 200000 miles on the factory turbo. Oil changes are the secret. Every 3000 mile OR 3 months which ever comes first. Too bad for you synthetic guys just bite the bullet and spend the bucks so says GM. Also pre fill the oil filter before installing it. The service says disable the ignition and crank engine until you get oil pressure. This only wears the starter out sooner. If you are quick with a pre-filled oil filter you won’t spill much
Where exactly does the problem lie when it comes to the point of having too hot oil? I mean the oil going into the turbo comes from the crankcase/motor, so it's not cool to begin with, and the turbo, while it's hot, I wouldn't think it's as hot if it's actually being used. So as long as you don't go from WOT, boosted run, to turning the car off, I'd think you'd be fine. Even driving on the interstate, cruising at 2500rpm, no boost, I wouldn't think you'd need to actually let the car idle before shutting it down. I'm guessing the problem area lies inside the turbo in a small area where the oil flows so if it's extremely hot, without a constant flow of oil to bring it into a more normal temp, the stoppage of oil flow will cause what little oil falls into that portion as pressure is lost, will sit and boil? I'd been told before to not worry about this and that even after a run at the strip, the 1/2 mile trip back to the pits is more than adequate to cool the turbo.
Your probably right. But I am talking about myself as an individual not trying to give advise to all saying you definatley need a timer. I can only speak for myself and everyones driving habits are much different. I have a friend that if he travels 10 miles with his TR, he might boost his car once or twice.(And that is alot for him)If I go around the block to get something from the corner store I would have at least gave car full boost maybe two or three times, never mind the 6 to 8 pounds in between! I would come right home and rush back into the house.I guess i am gunshy because the first turbo I ever blew, the car only had 67,000 from previous owner. After buying and changing the turbo, I then cranked for ten seconds to get oil to build up in line, then started it, then only one minute later I blew that new turbo!!! After inspecting the line I couldnt even blow thru it! Needless to say they did not warranty the turbo because the shaft was a nice shade of burnt blue steel.Very expensive weekend for me to say the least.So if peace of mind is gonna cost me around 150.00 bucks, I'll take it..But oil changes are definatley key here also, if your lazy with the oil changes, not even a timer will help you..
I just have to chime in here. I would think everyone would be using synthetic oil in their engines. LS1 'vettes specify Mobil One 5W30. I've heard Royal Purple is the best, but I've always used Mobil One because you can get it anywhere.
Synthetic will let your starter crank the engine faster in the winter, and most importantly, it will resist coking the drain line from the turbo.
Synthetic has a higher boiling point, and it lubricates better too. Other than the price, I can't think of any reason to use natural oil in a Turbo car. Does anyone else have an opinion for the use of natural oil?
Actually, I don't use synthetic. I tried it once but found that the stuff found every possible nook and cranny to leak out of. With regular oil I would maybe have a very small dot of oil where I would park the car but with synthetic oil I had a nice puddle. So I changed the oil back to regular and don't have to worry about running out of oil. Probably not a very good reason for not using synthetic, but until I have the time and money to fix all the leaks(which I've had the rear main replaced then I had the motor rebuilt, I'm not sure why or where it's leaking from, probably the rear main though) I'll stick to regular. And actually I haven't seen even the small dot under the car in a while, maybe it clogged itself.
Priz, I like your style. Taking responsibility for the leaks is the right thing to do. I had forgotten how Syn finds the smallest holes. The best builders in the business say it is almost impossible to keep a turbo engine sealed over time. Bigger turbos increase blowby, which increases crankcase pressures, and thereby start leaks. In '98, GM, in an effort to cure the oil leaks, started a design group called the FAGS. (Fasteners, Assembly, Gaskets, and Seals.) They designed the new style gaskets that can be used several times. They're called Carrier Gaskets. They have an aluminum backbone, or plate, with a groove on both sides filled with a bead of RTV. When installed between two machined surfaces, the RTV compresses into the square grooves and expands to original spec when disassembled. Zero leaks on the new engines. I wish someone could design a series of retro gaskets for our engines using the same idea.
Don, I am with you on the new style gasket. I wish they made them for everything. I remember a 98 Vette buy back we had because of Mobil 1.
Only thing that stoped the leaks was conventional motor oil.
Don, which style is that, that I said I don't use what you figure everyone should use or that I don't blame the oil, just say I need to fix my leaks?
Those gaskets sound great. When I had my motor rebuilt I also had the tranny redone by the same shop. There were transmission problems after the rebuild and during one of the shops testing runs, with me in the car, the guy blew a headgasket(maybe two). So my guess is the rear main was blown out a bit then. I took the car down to BGC and had them pull the pan and fix the rear main and check the lower end out for me. It was fine after that for a while but started leaking again eventually. I'd like to run synthetic because of its great properties but not until I can get the leaks fixed. Just out of curiousity, is there anybody out there whose TR doesn't leak any oil? And if you're lucky enough to answer yes, have you done anything specific to make sure typical areas such as rear mean, oil pan, and valve covers don't leak? I'm just looking for hints for when I get around to stopping my leaks. I only run a TA49 and I do use a pcv check valve. And like I said, my car doesn't seem to drip any more so it's not like I am missing a gasket somewhere.
Thanks for the help guys. We have a seized turbo (ran out of lubrication) from a Lycoming (TIO-540-A2C) engine on display at school and it is NOT a pretty site. I did not want this to happen to my TR ;)
Jason