SuperSubaru Posted November 6, 2006 Share Posted November 6, 2006 Okay here's the dilly-yo (97 OBW 5SPD 136,000 miles): New clutch New head gaskets New timing belt/pulleys New water pump New oil pump New cam/crank seals New front wheel bearings All together $4000 Prior to the maintenance I was getting a solid 25-26.5 MPG, every tank - I check every tank religiously. As all my car is used for is back-and-forth to work (90miles/day). First two tanks after everything was replaced, 20 and 23 MPG. I was hoping to bump it up a bit with all of this, not go down!!! Any suggestions - I have no CEL. What would cause a sudden significant drop like this? Since they had to work on all sides of the engine, it was pulled from the vehicle. Link to comment Share on other sites More sharing options...
Manarius Posted November 6, 2006 Share Posted November 6, 2006 I'd hardly call 2-3 mpg a significant drop. Maybe your car just needs worked back in a little bit. Come back to us having driven 7 or 8 tanks and complain. Link to comment Share on other sites More sharing options...
BigMattyD Posted November 6, 2006 Share Posted November 6, 2006 Maybe since you got the work done, you've been hopped up with excitement and been driving more aggressively.... matt Link to comment Share on other sites More sharing options...
WoodsWagon Posted November 6, 2006 Share Posted November 6, 2006 The battery was probably disconected when the engine work was done. This will erase what the car's computer has "learned" and will reduce power and efficiency untill it relearns the engine's charactaristics. Drive the car normaly, and it will come back. The carbon build up in the engine may have raised compression, leading to higher efficiency. There are certain driving patterns that will speed up the relearning process. Link to comment Share on other sites More sharing options...
fishy Posted November 6, 2006 Share Posted November 6, 2006 Maybe since you got the work done, you've been hopped up with excitement and been driving more aggressively.... matt This was my first thought too as silly as it sounds. With such a small difference in mileage over a short test period it could very easily be 100% driver. Link to comment Share on other sites More sharing options...
nipper Posted November 7, 2006 Share Posted November 7, 2006 Thats not significant. Give the computer a month to relearn your driving. Also the change of seasons will affect gas mileage, along with seasonal fuel changes. There is nothing on that list that should affect gas mileage. Check your tire pressures. nipper Link to comment Share on other sites More sharing options...
Bmm001 Posted November 7, 2006 Share Posted November 7, 2006 It's also possible that your gas stations have switched to the "winter" fuel blend. It is getting colder; my mileage is never as good in the winter, as is the case with most people in cold climates. Brian Link to comment Share on other sites More sharing options...
SuperSubaru Posted November 7, 2006 Author Share Posted November 7, 2006 Thanks for all the input, I will give an update in a couple weeks. When every single tank for 7-8 months reads 25-26.5 MPG, 2-3MPG (10%) is significant. But I will say the new clutch engagement did take a little gettin' used too. I had some O2 sensors laying around (brand new) so I will probably do that over the coming holiday weekend as well. I was hoping to see numbers approaching 30 all said and done. Link to comment Share on other sites More sharing options...
Virrdog Posted November 7, 2006 Share Posted November 7, 2006 Yeah, everyone covered most of the changes. I'll just add the new pumps and bearings might be working themselves in and might cause a slight parasitic loss of power. Give it a couple of more tanks and you might start seeing your old mileage numbers. And then they should go higher when they stop pumping winter gas. :-\ Link to comment Share on other sites More sharing options...
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