99 s70 2.3T New Project Car

[bmdubya1198]

Well, the owner's manual that shipped with my 1995 S70 T5 states that 87 is the minimum octane requirement and that to obtain "optimum performance" use 91 octane or higher. I have always taken that to mean that Volvo is stating that you can use 87 octane without causing problems to your engine, either short-term or long-term and that if you want every one of those 236 horses you need to use premium. I know that we all have certain areas where factory recommendations are taken as Gospel, other areas where we know full well that they are BS of the CYA variety, and still other areas where we know it's best to EXCEED the factory recommendations.

Right now, in my area there is a $0.44 difference between regular and premium which is maybe $8.00 per tank for a small car that only reaches MPGs in the high 20's at legal highway speeds and much less around town.

I'm just asking whether or not anyone has any real evidence that a particular Volvo engine in STOCK configuration will burn valves from using 87 octane gas, or whether it's nothing more than talk. I have no problem spending the extra cash if there's any scientific basis that using less than 91 octane will damage your Volvo engine.

I'll also grant that using premium may yield something like 3% better mileage which reduces the extra cost. Still, I'll bet burned valves has more to do with how hard you push your engine. I spend most of my highway time at 2600 rpm and seldom hit 4000 rpm. Yes, I'm an old fart and get plenty excited by 4000 rpm. I have been thinking about what someone wrote about the valves not rotating on their axis until you hit 4000 rpm and that you should at least periodically run your engine at 4000 rpm for a period of three minute. I should do that, but it might be too exciting...

viewtopic.php?t=74239]This thread is worth a read. There's an analysis on page 7 that's worth a look. There aren't any real conclusions on a definite cause, but we all have an idea of several things that could potentially contribute to burnt valves. Leaky valve stem seals, incorrect coolant, and low octane fuel all seem to be possible issues. Also passive driving styles. I take every precaution necessary to avoid the issue... Zerex G-05 coolant, 93 octane fuel, and I drive my cars hard. They regularly see 6,000 RPM. Do these engines make any power up there? No, but it makes good noises! Plus it helps prevent deposits that can decrease gas mileage when driven conservatively or possibly cause problems like burned valves.
The way I see it is it's cheap insurance. $5 more for coolant when I buy it, a couple more bucks for gas here and there isn't going to kill me.

[Eddystone]

I also use Zerex G-05 coolant in my Volvos. Lately, I am also using full synthetic high mileage oil. I suspect that my T5 would benefit from being rung out a little bit more, though with the automatic you really have to work at getting those rpms up for an extended period. Next time I fill up I'll put the "hi-test" in there and get the revs up, but not 6000 rpm.

I've put premium in it before, and I can tell the difference for sure, but my other car is a '98 V70 non-turbo, and the T5 always feels like a rocket ship even at part throttle compared to that.

[bmdubya1198]

I also use Zerex G-05 coolant in my Volvos. Lately, I am also using full synthetic high mileage oil. I suspect that my T5 would benefit from being rung out a little bit more, though with the automatic you really have to work at getting those rpms up for an extended period. Next time I fill up I'll put the "hi-test" in there and get the revs up, but not 6000 rpm.

I've put premium in it before, and I can tell the difference for sure, but my other car is a '98 V70 non-turbo, and the T5 always feels like a rocket ship even at part throttle compared to that.

Haha yeah, you definitely don't have to drive it like a lunatic, but it's a good idea to get the revs up at least every now and again. Keep up what you're doing with the synthetic oil and G-05 coolant though.

Anyway, back on topic!

[yanga001]

Thanks for the help, as far as my list goes (Great discussion on fuel and coolant), ill need to:

-Replace calipers
-Resurface the rotors
-Check timing belt
-Have receipts for changed water pump
-PCV glove test shows no positive pressure
-Change coolant/check it
-Change oil
-Fill er up on premium
-Tear down seat controls and do tests
-Run her hard for a bit to clear out deposits (previous owners apparently took it up to max speed at purchase but I'm pretty sure they drove it conservatively)

Ill post updates as they come. If i missed anything please let me know

[yanga001]

Update:
-All chair buttons passed conductivity tests. Im fairly sure its a dead motor. Will need to do a proper disassembly to test the motor.
-Calipers still need to be replaced along with rotors.
-recorded some odd noises while turning (sounds like a pump or motor) and am researching it

[bmdubya1198]

Sounds like you've got a good list going.

As for the seat motor, I think you're on the right track there. It probably needs the motor.

[abscate]

I’ll stick my neck out on this one a bit, I don’t think we have had any burned out power seat motors on MVS. They are really high quality kit.

Try this on the seat.

Put your lights on, then push the inop seat button while watching the lights, looking to see if they are drawing current.

If they are, while holding the seat button one way, try bumping you’re rear end forward and backward while sitting. If the car sat dormant for a while , they can get sticky and that can free them up. Correct solution is to remove seat andclean lube tracks, of course.

Don’t connect battery with seat removed or connectors pulled apart; you will get an SRS error which the dealer has to clear.

Semicolons and Oxford commas promote etiquette, verve, and elan; MVS becomes a verdant oasis of grammar, rich and lush, with their fertile loam.

[bmdubya1198]

That's a good point, I was thinking as I typed that that I really haven't ever heard of the seat motors dying on these cars. However, I've experienced the switches go out several times. My '98 also needs assistance to get the seat to move forward. All other directions have no problem.

[yanga001]

I’ll stick my neck out on this one a bit, I don’t think we have had any burned out power seat motors on MVS. They are really high quality kit.

Try this on the seat.

Put your lights on, then push the inop seat button while watching the lights, looking to see if they are drawing current.

If they are, while holding the seat button one way, try bumping you’re rear end forward and backward while sitting. If the car sat dormant for a while , they can get sticky and that can free them up. Correct solution is to remove seat andclean lube tracks, of course.

Don’t connect battery with seat removed or connectors pulled apart; you will get an SRS error which the dealer has to clear.

Semicolons and Oxford commas promote etiquette, verve, and elan; MVS becomes a verdant oasis of grammar, rich and lush, with their fertile loam.

Sorry about the grammar and format of the last few posts. I was typing this out on my phone, and may have been bit too excited to write it out proper.

After reviewing my pictures, i realized that the seat recline wire colours do not match up with the schematics for an early 2000 vehicle. The colour scheme i have for connector B (refer to page 292 item 3/89) is brown and pinkish, while it states it should be brown and green. I believe this might be evidence of an earlier repair or something, however when i tested the neutral state of the wires, i had full conductivity between the two.

relay diagram for passenger chair (No Memory)

volvo.png (320.79 KiB) Viewed 95 times

(it seems the switches just change the "polarity" (which side has the higher voltage) to effect motion in a certain direction. Power distribution is done in the seat controls with a BJT + IC used as a current sensor to detect when the motors reach their limits. )

This matches up with the diagram, leading me to believe that the motor or wires leading to the motor in the seat are dead. I did not hear any sounds indicating a stalled or seized motor so i don't believe that it is a case of a busted switch. However, i mistakenly did not check voltage on the switches so i could be wrong if the switch has a break in its connections to the power supply lines.

I did try bumping the seat while holding the switch, and noted that it did not move the seat or create any noise in the motor.

I did some more research into the noises made while turning, and it seems likely that it is the power steering reservoir. I will do some more googling to see if it can be replaced or cleaned. I took a video and it seems to match up exactly with a few other videos from people who had the same issue.