1999 V70 B5254T VVT Head Removal Advice Needed

[precopster]

Interesting observations jxkeefe.

The hydraulic lifters were phased out at the end of the 99 model year when the 5244S and 5244T engines were released, so the valve burning issue seems to affect both hydraulic and manual valve lash adjusters. The 2000 plus cars have factory calibrated shims for each valve. Clearances are not a service item as the head would need to be removed for this due to the lack of cam cover (white black engines have cams that are held in place by the cover)
My engine rebuilder loaths having to set up 2000 plus shims however another engine builder I know charges $16 per valve adjustment multiplied by 20.


It seems that from my understanding there are more pre 2000 cars being affected by burned valves than post 2000 and most of them are turbo variants so yours is more of an isolated case than most others.

Interesting that your car had low fuel pressure at low temps because this is the sort of condition that creates pinging in the cylinders. I wonder if this is related at all.

[Andy for help]

Low fuel pressure equals lean combustion equals high combustion chamber temperatures. Good call Mike, in the old carburetor days lugging a vehicle (wide open throttle with no acceleration) could burn up valves and even put a hole through a piston in one long climb of a hill. Pinging equates to temps over 2500 degrees F. On the vast majority of fuel injected engines, the engine management system depends on the fuel pressure being maintained by the pump and fuel pressure regulator. Especially during open loop, the PCM relies on a program based on a calibrated delivery / flow at the injectors. During closed loop a false rich signal from the O2 sensor could also cause a lean fuel delivery. An oil leak after the combustion event could cause this "false rich condition" as perceived by the O2 sensor. This could include exhaust valve seal(s), as well a turbo leaking oil on the exhaust side.

[jxkeefe]

Thanks for your input "Andy for help" and "precopster".

The low fuel pressure only occurs 20 sec after cold start while still in my driveway. It is an intermittent problem. The engine stalls due to too lean. After restarting the engine, the problem disappears for the rest of the day. I had a datalogger monitoring fuel pressure among other variables and no issue with fuel pressure when a piece fell out of the valve head. Further, a lean mixture would throw all sorts of codes due to low fuel pressure.

The more I think about it, the more I am convinced the valve material is the issue.

Jxkeefe

96 850 wagon blue
05 V70 wagon grey

[precopster]

I just went through a fuel pump problem with our XC70 2002 and the only code I received was a lean code; on multiple clears with a scan tool only the one code. The motor was constantly pinging. The Volvo diagnostics are not as advanced as some would believe.

You can monitor air/fuel ratio and set limits for audible alerts using the Torque App and ELM327. I bit the bullet and replaced the fuel pump with a complete assembly.

20 secs after cold start is the exact time it takes for the O2 sensor's element to heat up and swap over to closed loop.
Your lean condition is atnthe beginning of transition.

[Ben850]

Found the cause of no compression in cylinders 4 and 5. Pistons look to be in good shape. Any ideas on how to prevent this from happening again? Car has 206K on the clock. This is my first run-in with burned valves.

Good gas and oil changes on time would be the simple answer. Choice of oil as well but that is a can of worms I will not open on this thread.
I realize this has been thought through. I feel bad while seeing the valve failure. I have another vehicle that may have suffered a similar injury. A new purchase I do not want to do a Head Job on.
I will soon find out.

[beoutside]

This happened with our inlaws 98 and our 99, one of the hydraulic lifters failed causing that exhaust valve to overheat and burn a hole in it. I replaced all the hydraulic lifters/followers to prevent this from repeating itself on the rebuild.
Thanks for the tips on setting the timing with the cvvt hub.

[beoutside]

a nice view of setting the timing with CVVT hub on exhaust camshaft

[beoutside]

I replaced all my lifters after my very experienced machinist showed me the failed hydraulic lifter that caused my valve problem. The previous owner was not a reliable quality oil user and did not change the oil at recommended or needed mileage. That was at 180,000... still fine at 260,00 after DIY head rebuild. Only replaced bad valve but did all the guides.

[beoutside]

However upon the timing belt change it seems I have no spring tension in my CVVT.... ?

[se13allmylife]

Found jxkeefe's comment on Ford possibly being cheap with the valve manufacture interesting , my daughter has a 2008 1.4 Fiesta , after only 27,000 miles it developed a miss . After a compression check No1 had zero reading so we took the head off and found the complete head had come off the valve !!!!!! The stem when matched to the head was perfectly straight and the belt and timing were fine , on closer inspection of the break we observed that just over half of the exposed metal was blackened whilst the remainder looked fresh which suggested to us the stem had a hairline crack from manufacture . Because the car was five years old at the time Ford UK were totally disinterested even though it had been in the dealer network all it's life and the mileage was genuinely low , they claimed it was an 'old' car which pretty much well told me all I needed to know . Needless to say it's never been back to a stealership since and after replacing all the exhaust valves the engine has been fine to date . My 21 year old 180k 850 that has been well cared for shows virtually perfect compression across all 5 cylinders , friends and family berate it's age and looks but I seem to work on their newer vehicles a lot more than I do mine , maybe their hatred is jealousy !!