Burned Valve Database DATA ONLY or a P0455 code will be set

[scot850]

Oh dear..................!

Neil.

[Clemens]

C-r-a-p

[Pecata01]

This happened 02 January 2022. Car went back on the road at the end of January and I'm still driving it.
a. 2001
b. S60 2.0T 180PS (B5204T5)
c. I think around 320000 km
d. Around 10k km.
e. LPG (propane-112 RON, so it's much higher octane that I can get from the gas stations. (max 100 octane RON).
f. EKO, Rompetrol (Greek, Romanian).
g. 50/50
h. Average with lots of WOT accelerations.
i. Three people including me in the car during the failure.
j. Highway, winter, so around 0 deg C.
k. It had. Smoked pretty bad at startup. Oil consumption around 5 liters per 10 000 km. Now is around 2.5 liters per 10 000 km
I. Was driving with 5W30 that got changed to 5W40 A3/B4 just a week before the accident.
m. Merging into the highway. WOT acceleration up to redline at 3rd and 4th up to 200 km/h , ambient temp around 0 deg C. I saw the check engine was flashing after i let go of the throttle at 200km/h.
n. 1 valve at the 3rd cylinder (I think it was the fifth exhaust valve from the timing belt.). Cylinder #3 had 6 bar compression while the others were around 13 bar.
o. Red and clean G12+ coolant.
p. Removed head. Got it to machine shop for a full overhaul (new exhaust valve, other valves lapped, new valve stem seals, head gasked, etc...). New LPG injectors.

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Log from OBD. Stoichiometric mixture all the way to redline.

[abscate]

My T5 valve burn was clearly a poor seat which let hot gas burn the valve stem. It burned out almost 3mm of the stem metal

Picture to come

[songzunhuang]

Well this thread is a blast from the past. I originally saw the thread when I got a P0305 back in May of 2016, but that didn't turn out to be a burnt valve. It is now June of 2023, 7 years later. About 2 months ago, I finally experienced a burnt valve on #1.
I documented the fix in this thread: viewtopic.php?t=102390

I would be remiss if I didn't add to this long standing thread about burnt valves. Here's my data.

a) Year - 1998
b) Model - V70 T5
c) Mileage Total - 272,784
d) Mileage under your ownership - all of it. Car bought new.
e) Octane Gas you typically use - 87 (Regular gas in California)
f) Supplier of Gas - Mostly Valero and Shell, but changes often.
g) Driving Cycle (% city/ % hwy) - 20/80 (It's been 25 years, I may be a little off but when commuting it was mostly highway).
h) Driving Behaviour (average, passive, aggressive) - average
i) Typical Load in Vehicle: single occupant, or multiple occupant - single when burnt valve happened, but really loaded on family trips.
j) Location and Typical driving weather - California, almost always nice and sunny, but several trips to Tahoe in winter.
k) Does the car have leaky valve guides (ie: blue smoke at start up) - No
l) What kind of oil do you use - Recently just Dino oil from O'Reilly's
m) Describe in detail how it happened: (ie: ambient temperature, throttle input, load, etc.) - Daughter using for school. Typical drive is about 25 miles one way over a mountain road. She drives very conservatively.
n) How many valves burned and which Cylinder - 1 valve on cylinder 1
o)What brand coolant do you use, when was it last changed. - Xerex Gold and then the pre-mix from O-Reilly's house brand
p) What did you do with engine/car - rebuilt the head. It's good as new. See the thread linked at the beginning of this post.

So far I have taken the car on a few drives and errands and it is performing quite well. As I write this is has now got 273,839 miles on it.

[Clemens]

Quick question: Over here they starting adding 10% Ethanol to the fuel as opposed to 5% previously. How much Ethanol is in US gasoline? Just wonderi g if this could effect burnt valves.

[bmdubya1198]

US can have up to 10% ethanol, generally.

[coop]

a) 1998
b) s70 t5
c) 203k on odometer but prob about 215k actual
d) 10-15k
f) various
g) 60/40 city
h) defensively aggressive
i) single small amount of supplies
j) Denver. 20f-100f
k) no leaky valve
l) castrol gtx euro
m) engine had noticeable valve tap. Changed oil. Took on highway and 30 seconds at 70mph and boom
n) 1? Exhaust cylinder 3
o) zerex g5. 1.5 year ago
p) still driving. Put almost 3k miles on it.

Idles rough when cold. Better after it’s been warmed up. Gas milleage dropped from avg 22.5mpg to 17. Noticed earlier on a 70 mile highway trip it was averaging doing 23. It was closer to 30 on the highway before.

Exhaust snells of unburnt fuel/fouling cat

Currently car is showing following dtc codes
P0300 random misfire
P0301 misfire cylinder 1
P0303 misfire cylinder 3
P0410 secondary air system
P0455 Evap system

[abscate]

1996
Western New Mexico 850
Exhaust #2
More to come

[Sveedy]

Ok, I get it

a) 1996
b) Turbo
c) 30k on rebuilt engine
d) n/a
e) 91
f) 76
g) 20/80
h) Moderately (aggressive)
i) One
j) ARIZONA !
k) No smoking. But did have high oil consumption.
l) Mobil 1 (last oil change got 0-40. Didn't like it)
m) Spirited merge. 80* ambient
n) One valve. Cyl.#2. Heavy carbon build-up on stem. Also seen on another couple of stems.
o) Xerex G5
p) Rebuilding head

To be fair, car is also tuned and has many aftermarket bells & whistles, so not stock in any way. But I'm fairly sure that non-Volvo seals were used in the rebuild.