Exhaust Manifold Gasket Replacement
lnyboer » I’m a newbee here, but have found useful articles here in the past. Perhaps something has been written up on exhaust manifold gasket replacements that I’m not locating. My 2000 V70XC with B5244T engine, has had engine light code issues (P0422) since I bought it at 80,000 miles. The frequency that it would come on increased until it was on constantly. At 129,000 miles, a Volvo service tech told me I had an exhaust manifold leak, and most likely gasket replacement would end the code problem.
I dismantled and cleaned all mating surfaces without scratching or gouging anything and bought new OEM gaskets and 5 new studs and nuts of the 10 it takes. I remember wondering which direction the gaskets should face, and it seemed they only fit one way. I reassembled and tightened the nuts in two stages ending at 25nm. I completed reassembly without running the engine which I recently read was not a good choice, but had not read about running then retightening at that time.
Engine codes were gone for at least 300 miles then P0422 code returned. After driving 500 miles on the new gaskets, I tightened them again. I found all the 8 inner nuts shy of 25nm and the two outer nuts still at 25nm. Reassembled and drove with light out for about 700 miles and code P0422 reappeared again. What have I not done correctly and what would you suggest I do now? Should I start all over again and get all new studs and nuts and gaskets and reinstall with a locktight agent or silicone gasket compound?
Perplexed!
Lee
JDS60R » Have you read this from another board – he says unmentered intake air could be the culprit – you might want to check for intake leaks if you can’t see an exhaust leak
I have been chasing a P0422 on my 2000 XC70 (140K miles) for a few months.
I may have finally resolved it in the past week.
It was an obtuse, but inexpensive problem to fix.
My approach was to eliminate all the places where un-metered air could get into the intake manifold…. clean and clamp the vacuum hoses; etc.
After checking and rechecking everything, and making some significant improvements in the performance and economy along the way, I still got an occasional P0422 under specific driving conditions.
One more check last week and I discovered that one of the two plastic clips on the intake air temperature sensor was broken off.
I bought a new one from volvo for about $20. It took 2 minutes to replace.
With only one plastic clip, the sensor will work fine at highway speed and a good vacuum in the intake. At suburban driving, the seal is not so good, and a positive pressure in the intake (like when you let you foot off the gas), might even push the sensor partially out.
IMHO, the only way that sensor got broken was when it was in the dealer for service. From the looks of the break, it has been broken for a while.
I think that this solution to P0422 would more likely apply to turbo vehicles, as the non-turbo’s would not have the positive pressure in the intake.
XC70 2000 Persistant Exhaust Manifold leaks
The Volvo XC70
At its introduction, the second generation V70 XC received a major upgrade. It featured better ground clearance of 8.2 in (210 mm) thanks to a raised suspension, different bodywork with unpainted bumpers and fender extensions, and AWD as standard. An interior grab handle for the front passenger was installed only on this model. Early V70 XC featured special rear view mirrors, a feature that was discontinued after 2003.
Engine and gearbox choices were limited. Only the 2.5L low pressure turbo, or the D5 diesel engine with either a 5-speed manual or 5-speed automatic transmission were available. No diesel version was offered for the North American market.
For 2003 the model was renamed the XC70, in keeping with Volvo’s newly introduced XC90
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