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4960 messages, Last post on Nov 25, 2009 at 8:23 AM

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What is this discussion about? Brakes, Electrical, Engine, Exhaust

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#3272 of 4960 Exhaust Leak into Cooling System - Coincidence? by cslemaker Mar 15, 2007 (9:31 am)
I have a 1989 Trooper 4-cylinder. Is there any way the actions involved in disconnecting the stuff connected to or near the valve cover, removing the valve cover, adjusting the valves, then closing things back up could cause an exhaust leak into the coolant passages to develop? I had a valve adjustment performed and immediately thereafter noticed the temp gauge doing funny things. Under the hood I found that coolant had filled the reservoir and sprayed the engine and underside of the hood. After trying a few other things (such as a new radiator cap), my mechanic pulled the spark plugs, pressurized the cooling system, and informed me that one of the cylinders then contained coolant. (I would bet it was the same cylinder that had low compression and necessitated the valve adjustment. I would also bet that it was the exhaust valve causing the low compression.) I find it very hard to believe that this was 100% pure coincidence (valve adjust & exhaust leak). Thanks for your opinion and answer to my opening question.
#3273 of 4960 Using engine to brake? by billwv Mar 15, 2007 (10:48 am)
Hi, I didn't know where to post this question, but I am sure many here can answer. With an automatic transmission is it wise to shift to a lower gear when going down a hill to hold the car back and not have to use the brakes as much? For example: going down a 2 mile hill with 35 mph limit I shift my Scion xb with four speed automatic into 2nd gear. It will coast at just about 35 down the hill and I don't have to use the brakes. My brother says I will wear out the transmission -- I say they are designed for that -- who is right? Thanks, Bill Replies to this message: kiawah (Mar 15, 2007 12:16 pm) jipster (Mar 15, 2007 5:14 pm)
#3274 of 4960 Re: Using engine to brake? [billwv] by kiawah Mar 15, 2007 (12:16 pm)
Replying to: billwv (Mar 15, 2007 10:48 am) Brake pads are much cheaper and easier to replace, than transmission and engine wear. If I had a heavy vehicle in a lot of mountain passes I would consider it to keep from overheating the brakes (did this w/Suburban pulling a trailer), but normally you should just leave it in drive and use the brakes. Many years ago, I used to have an old SAAB V4 manual transmission, of which the transmission actually allowed the vehicle to overrun the engine (ie. no slowing the vehicle). I think it was called free-wheeling, IIRC. You actualy would just take your foot off the gas and the car would coast going down hill....then just put foot back on the gas to go up the next one. This enabled better mpg, and lower engine/transmission wear. That was one of the few good things that car did, but that is a whole another story. Replies to this message: jipster (Mar 15, 2007 5:14 pm)
#3275 of 4960 Re: Using engine to brake? [kiawah] by jipster Mar 15, 2007 (5:14 pm)
Replying to: kiawah (Mar 15, 2007 12:16 pm) Brakes are cheaper than a transmission, but if you lose your brakes from overheating going down a steep mountain road you're in big trouble. I'd check your owners manual. The manual on my 99 Buick Regal states not to drive in second gear for more than 25 miles or at speeds over 55mph. So, 35 mph should be safe.
#3276 of 4960 Which engine is better ? by jiamin Mar 16, 2007 (8:34 am)
Assume two engines are of the same displacement. One is V6 and the other is V8. Replies to this message: qbrozen (Mar 16, 2007 12:21 pm) Mr_Shiftright (Mar 16, 2007 1:29 pm)
#3277 of 4960 Re: Which engine is better ? [jiamin] by qbrozen Mar 16, 2007 (12:21 pm)
Replying to: jiamin (Mar 16, 2007 8:34 am) uhhh... can you give more details? Displacement isn't everything, and neither are cylinders. How is the fuel mileage in each? How much HP and torque in each? Should reliability be taken into account? What about weight?
#3278 of 4960 Re: Which engine is better ? [jiamin] by Mr_Shiftright HOST Mar 16, 2007 (1:29 pm)
Replying to: jiamin (Mar 16, 2007 8:34 am) I think the advantage of a V6 over the V8 would be (might be) fuel economy, cost to produce and weight, that's about it....and given they are of similar displacement, some of those advantages might be slight.
#3279 of 4960 Which engine is better ? by jiamin Mar 16, 2007 (5:58 pm)
Thanks for the reply. I know there are many things involved. What I'd like to know is which engine can produce more HP and torque, if I can also assume most other configuration are very similar. In addition, I guess V8 should be a little smoother than V6? Replies to this message: qbrozen (Mar 17, 2007 6:56 am) jiamin (Mar 17, 2007 7:38 am) kiawah (Mar 17, 2007 8:01 am) Mr_Shiftright (Mar 17, 2007 10:16 am) qbrozen (Mar 17, 2007 10:45 am) and 2 more...
#3280 of 4960 Re: Which engine is better ? [jiamin] by qbrozen Mar 17, 2007 (6:56 am)
Replying to: jiamin (Mar 16, 2007 5:58 pm) ok. so we're talking theoretically here. you've got 2 engines that are identical in every way except for number of cylinders. WELL, I'm going to go out on a limb here and say you may get more torque out of the V6 and more HP out of the V8. Why? Because a bigger combustion chamber makes for a bigger bang. However, more, smaller chambers typically makes for higher revving. I could be totally off base. I mean, with more chambers, you get more bangs per revolution ... but that's the problem with theories. They aren't always right. oh, and I'll also say I think the V8 could theoretically get better highway mileage because you can put in taller gearing because, again, more bangs per revolution makes it easier to maintain speed with lower revs. And, yes, the v8 COULD be a little smoother. Did I answer which is better? not really. ;b Replies to this message: jiamin (Mar 17, 2007 7:38 am) kiawah (Mar 17, 2007 8:01 am) Mr_Shiftright (Mar 17, 2007 10:16 am) qbrozen (Mar 17, 2007 10:45 am) Mr_Shiftright (Mar 17, 2007 11:00 am) and 1 more...
#3281 of 4960 Re: Which engine is better ? [qbrozen] by jiamin Mar 17, 2007 (7:38 am)
Replying to: qbrozen (Mar 17, 2007 6:56 am) Thanks gbrozen, and that's what I want to learn. I am not a DIY on cars but I like to read about car stuff. Engine configuration is one of them. By the way, due to their nature, I4 is never as smooth as V6, correct? To come back to theory, if I4 has perfectly designed counter balance (Forgot the name of the part), why can't it be as smooth? Replies to this message: kiawah (Mar 17, 2007 8:01 am)