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Discussion Starter · #1 ·
I picked up this beauty of a V50 with 119k miles on it as a tow-away project. Previous Owen had it over-heat, towed to the closest shop, where they told her that there were 19 engine codes, a hole in the radiator, and she should bring it to a Volvo dealer because it was beyond their level of expertise. After towing it home, it went on Craigslist. I pulled the trigger without much mechanical inspection since I was looking for a project and she had maintenance records for last 5 years and looked pretty good.

Got it towed home, rolled it into the garage and got to work.

Pulled codes with VIDA, and there were a number, but no consistent theme, some evap, engine no-start, headlight bulb intermittent failure, airbag, etc. Lots of noise, and no smoking gun there, so I didn't read into it and got to work. Game plan was to 1) confirm coolant leak and source, 2) diagnose likely head gasket failure or worse.

Found the coolant leak (upper radiator hose T fitting was cracked). I had a T5 S40 in the past, so I knew what I was getting into, but that airbag is a b*$#%.


Did a compression test with a cheap loaner kit from AutoZone - each cylinder fell between 100-115 psi. Not great, but seems reasonable to me based on the cheap kit, I'm at 6000 ft above sea level and over 100k miles on the car. At a minimum, everything was within 15% of the high, so looked good. Things are looking up!

Tracked down a radiator hose and replaced it, filled her up with coolant, changed the oil and buttoned everything up. Coolant that I pulled out was green with some white floaties/precipitate likely from mixing chemistries, but no oil contamination that I saw. Oil was DARK and looked dirty, even though sticker on window says oil change isn't due for another 2k miles, but figure that's from over head. No milkiness or sweet smell.

Once everything was back together, she fired up without a hitch and I did a color-change block test for ~5 minutes to double-check block/head gasket integrity and make sure no exhaust gases were coming through cooling system now that everything was back together. Again - looked good. Took a spin around the block and repeated with same results.

At this point, I was cautiously optimistic that head gasket was intact, and the overheat hadn't caused any other substantial damage. Car drives great, passed emissions, engine feels like it's running on all cylinders, and suspension is in good shape. So, I'm pumped.

After driving for a few days, last night she threw a CEL. VIDA showed three codes - Misfire on start, Misfire cylinder 3 and Misfire cylinder 4. I've noticing an occasional stumble at idle after starting that goes away as soon as you start moving and giving any gas, which I'm assuming is the cause of the code. I have not noticed the stumble at idle mid-trip.

Trying to decide on the plan of attack from this point. Obviously spark is always a good place to start, but it seems unlikely this is the case with the issue only present a start and initial idle. Reading VIDA, low compression is also a potential cause. Being the misfires are on 2 adjacent cylinders, I'm now wondering if there is a small leak in the head gasket between those two. Need to figure out another way to confirm or eliminate that theory. Any other thoughts?

Looking forward to the journey!
 

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Yes. You are on the right track - some things to note:

Coils at that age are probably ready to go anyways. I bought mine at 117k, replaced all 5 as 3 were bad. One of the replacements went about about 150k, the other 4 replacements are still going perfectly strong.

Yes - it has been noted that a seeping headgasket that lets coolant into the combustion chamber can give misfire codes upon startup, but not cause any significant issue after warmup.

Injectors CAN leak and cause startup issues if they fill the cylinder with a bit, relieving the pressure in the fuel line - however if you don't have any startup issues where you have to turn it to II and wait a sec and then start, I doubt this is your issue.
 

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Discussion Starter · #3 ·
Ok, so picked up a leak-down tester today and got to work. Results were so bad I'm wondering if I'm not doing something right.

40-60% leakage on every cylinder. Most prevalent whistling is through oil filler cap/dipstick. Tested at 35 PSI, and didn't hear anything coming through coolant tank with cap removed.

All that sounds to me like smoked piston rings/cylinders, which is also supported by what looks to be some recent seepage around the cam seal. But, it doesn't explain the misfire on startup. Also amazed the car is driving as well as it is if there is that much blow-by...
 
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