98 v70 GLT rough idle when in gear

Post by **stephansvolvo** » 15 Jan 2015, 09:24

I passed a few cars with acceleration up to 100mph and after bring the speed back down to 75 I could feel there was hesitation, shutter like. When I slowed down to a stop rpms dropped and the car idled rough. Put it nuetrul and it was fineish.
I read codes as the check engine light was flashing, and gave me mid fire codes in 2,3,4..
I have to make the trip back to where I just came from an hour away. I will take the back way so I can limp it. Any ideas what might going on?

FYI I posted a couple of months ago about the misfires and the outcome was possibly the cam seals needed replaced. I haven't had the time to do this and the weather has been way to cold.

Post by **kahl** » 15 Jan 2015, 11:45

I would inspect ignition parts: spark plugs, plug wires, cap and rotor.

Post by **E Showell** » 15 Jan 2015, 12:09

Unfortunately, a high speed run like that may have caused an exhaust valve to burn. Do a compression test as soon as you can. I burned an exhaust valve after 10+ minutes of highway driving at 85 mph+.

Post by **stephansvolvo** » 17 Jan 2015, 22:45

So I am going to have my engine compression tested on Monday. I haven't come across any videos of replacing the valves if they are burnt. Is this a job I can do as an pretty handy guy with some knowledge of engines. How long do you think this could take in a fairly perfect world?

Thanks

Stephan

Post by **kahl** » 17 Jan 2015, 23:16

See if you can find a two part video that RSPI compiled. As with all of Richard's videos his explanation is very easy to understand. I have not rebuilt a 5 cylinder head but I have been wanting to pull one from a boneyard and rebuild. I am lucky enough to have a small head shop close to me where I have an invatation to bring in a head and assist in the rebuild. Let me know if you need to borrow the rear cam lock and head removal tools.

Post by **stephansvolvo** » 17 Jan 2015, 23:24

Thanks. I watched a few of those and I didn't really see a point where the valves were removed and inspected. I will watch them again.

villagepc · Post by **villagepc** » 17 Jan 2015, 23:29

Are the misfire codes from now (2,3,4) the same cylinders that were misfiring before in your previous post?
In addition to checking your ignition parts (cap/ rotor / wires / plugs) - double check that vacuum tree that's near the throttle, as well as the vacuum line that's at the left - front of the motor, near the thermostat. Its a little hidden back there and the elbow tends to blow off the end of the manifold under high boost / misfire / backfire in the intake. Give all your vac lines a once over to make sure none of them popped off.

With your spark plugs - I would switch out the actual sparkplug from cyl 2 to 1, and the same for cyl 5 for 4. This way you'll determine if those plugs are crapping out (if you get a misfire code for 1 and 5 after). Most importantly, verify your plug gaps!!!!! I had trouble under high boost where compression was blowing out the spark on an incorrectly gapped plug.

Post by **stephansvolvo** » 17 Jan 2015, 23:49

Yes. The codes are the same. My plugs, cap, rotor and wires are all only 4 months old. I will check all those vacuum lines. I actually didn't even think about all of those. I checked what I could see with a cursory glance. I will dig in to those tomorrow.

Post by **stephansvolvo** » 23 Jan 2015, 18:05

So I had the compression test done today. Results are as follows:
Cyl1: 130
Cyl2: 70
Cyl3: 125
Cyl4: 0
Cyle5: 135
Mechanic said it looks like the timing jumped time as well. What's the percentage of possibilty of bent valve?
What are your thoughts on this assement? Am I in to rebuilding a whole engine, buying a new one, buying a new car?
I'm sickened by this news.

Post by **scot850** » 23 Jan 2015, 23:22

Initially I thought, "burnt" valve, but normally would mostly affect only 1 cylinder, but 2 low readings on 2 and 4 is weird. The fact that the mechanic believes you have the timing moved, it is more likely you have a valve that has failed and this has caused 2 bent valves as my best guess. Either way you look like you may have to pull the head to find out. A couple of bent valves can be replaced, as often there may be some dings to the top of the pistons, but nothing else. What is strange though is that if you have bent valves, you wouldn't be able to turn the motor over. So perhaps you have 2 burnt valve, but then the question is why would the timing jump? Perhaps it is the reverse, the belt jumped causing the valves to fail. What happens if you re-set the timing? Maybe the valve sequence is out so you are not getting compression?

If this was my car, I'd pull the head and see what I am dealing with. If it is bad it may be cheaper to buy a 'new' car or replace the motor with a known good one.

I'm curious about what there is a habit of these engine to have valve problems in cylinder 2 more than any others.

For those who have burnt valves in the past, do you run regular or premium gas (87 or 91 octane)?
On my turbos, and as I do a low mileage, I only use premium gas, but when I had a N/A 850 I used regular a it was mostly used aroundtown, but if I was going to do highway driving at higher sustained speeds I filled with premium. Perhaps if driving the car hard on regular gas on the highway is causing an over-heat of the valves? But why cylinder #2 mostly? As the engine is injected it shouldn't be due to a lean burn on one cylinder. I'm baffled!

Neil.