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Engine Specific Info and Questions => IDI Engine => Topic started by: fillmore on May 30, 2005, 02:32:51 pm
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hey ive got a 89 N/A and lately ive been noticing a decrease in the mileage that im getting out of the thing its not really bad to the point that im really worried that theirs something wrong but nonetheless. i recently did a full ring job,head gasket etc, but since then its been probobly around 3-4 thousand kms and i havent re tourqued my head yet. i guess im wondering if me not retourquing my head could lead to bad compression and mileage. Ive been very busy and havent gotten around to tourquing the head yet but if its the problem then ill have to take a day off to do it.
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No need to take a day off. One evening (soon!) pull the valve cover and prep the torque wrench before retiring for the night. Then set your alarm clock 15 minutes early. Torque the bolts in the cold of the morning before starting the engine, and go to work normally.
Piece of cake! :wink:
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Did you retime the pump timing after doing de head gasket ?
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i like your thinking :wink:
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yep timings dead on. i didnt take out the crank so i just had to mark the cam and injector pump sprockets
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yep timings dead on. i didnt take out the crank so i just had to mark the cam and injector pump sprockets
You loosened the camshaft pulley and locked the cam in place, then set the pump at TDC and the crankshaft at TDC and put the belt on, then tightened the cam pulley bolt once you had the belt properly aligned on the crank and injection pump pulleys. Then you set the pump timing with a dial gauge. If you did that then you know it's not a timing problem. If you took the injectors out, you thorougly cleaned the threads and the sealing surface on the cylinder head, installed new heat sheilds, and torqued the injectors to specs. Then you know that's not the problem.
Might be a compression leak because you haven't retorqued. The retorqueing is mostly a formality as you'll probably find that the bolts are all good and don't require any more torque. I've never found a loose bolt in all the times I've retorqued, but I always do it just in case.
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what is the break in km for new rings? After I did a ring job the car ate a quite a bit of oil for the first 2500 km then the next 2500 km it started eating less and less. (oh and my mileage increased!!!-- 1200km for 45$ at 83 cents a litre--I think 4.2L/100km)
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J: What are you driving, a Smart car? :P Between the summer fuel, AWY to AGS swap, and a now correct reading speedo gear I'm getting 5.8l/100 km. That's delivering pizza which is about 50/50 city/highway. I was previously getting 6.5 which was more like 7 if you factored in the whacky speedo. Maybe I'll be able to get 4.2 when I put in some new front wheel bearings. My alternator will be pulling a lot less power because I'll be able to turn down the radio. :lol:
Steve
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it was a 1986 vw jetta - mech lifters, no PS, radio is rarely on, all new bearings, tires in good cond (alignment might have helped)
it was about 70% highway driving though, so the rad fan didn't turn on quite often :) - cruising at around 110 approx.
currently all I use is rotella T 15w40 motor oil (yes the cheap motomaster crap burns but for some reason rotella does not). I'm also searching for an even better oil and I've found one oil that seems promising for increasing compression - www.oilextreme.com - they found a way to get calcium carbonate particles inside the oil to fill up the asperities in the cylinder walls without wrecking the engine with a bunch of chalk. Now if only I can get them to ship to Canada :(
The way I drive my car could also have something to do with it. Revs never go above 2k when accelerating unless going onto the highway of course (I take full advantage of the low torque)
btw, I've seen one of those so called smart cars... 60 mpg? Those idiots could have done better than that. I've seen a few pages with people modding their geo's to run 60-70 mpg. Maybe they should just slap in a 3 cyl diesel engine and face the music- diesel is better!!!
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The Smart car does come with an optional 3-cyl turbodiesel, and gets about 80 mpg, IIRC.
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wow lol... learn something new everyday!
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one thing that i need to get better milage is a air intake. right now i dont have anykind of intake on the thing just the plastic airbox piece. anyone know where i could find one?
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An industrial hose shop will have various types of intake tubing/hoses.
Steve
ps. In Canada the only option for the Smart Car is an 800CC Turbo Diesel. They will get down to the mid 3l / 100km currently and the newer ones will be better than that once we get cleaner fuel.
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that mileage is not too bad... One thing I forgot to mention is that I use power systems cetane booster. (yes this stuff definitely helps!!!) car motors along around 10-15% faster in town.
for the air intake, all I did was buy one of those cold air intake kits, which didn't fit my car at all so I just cut it until it did! :lol: gave crappy mileage in town, but highway driving was much better (must have been heat soak from the rad. I'd recommend building some kind of ducting system)
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Give the bottom end some time to break in before checking fuel economy. I'd say wait another 20,000 kms to see if it gets better.
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Question about retorquing the head bolts: I'm about to do that to the engine I recently rebuilt. The manual says to turn the bolts another quarter turn (maybe it's a half turn, I don't have the manual in front of me). Anyhow, since the original torquing, I've decided that I don't trust the accuracy of my torque wrench, so the additional quarter or half turn that I'm supposed to do may not be right. I'm going to get a new torque wrench. What is the ft. lbs supposed to be on the second torquing?
Thanks
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hi
most vw's have stretch bolts. so there is no official torque
u torque to the spec then in sequence u turn the head bolts
so much of a turn and then again. what ever the book says.
Giles