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Edward
Edward, ASE Certified Technician
Category: Volvo
Satisfied Customers: 2852
Experience:  I've had 10 years of experience on the car line at 2 Volvo dealerships, Quality level Volvo tech.
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Volvo 850GLX: my 850 volvo runs fine.However when i accelerate

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my 850 volvo runs fine.However when i accelerate mostly uphill, i here the valves rattling. sounds like a deicel engine, but it is GAS. please help.

Edward :

Hello and thanks for your question. My name is XXXXX XXXXX I will do all I can to help.

Edward :

Let me first ask, is the check engine light currently on while driving?

Customer:

no it does not come on at all while engine is running.

Edward :

alright, If the check engine light doesn't come on at all while the engine is running, then I doubt there are any trouble codes stored.

Edward :

Does the oil light every come on ? at idle especially?

Edward :

The oil pan O-rings and pick up tube O-ring were bad to get hard and crack on these overtime.

Customer:

Does this engine come equipted with knock sensor?

Customer:

No dash , warning lights come on at all.

Edward :

Yes it does. they are under the intake manifold. Which is why I asked if the check engine light was on, If the check engine light was on, then I would have suspected knock sensor codes.

Edward :

Is it turbo or non?

Customer:

i do not get any dash board warnig lights at all. No turbo..

Edward :

alright, If you don't have any check engine light, then I feel sure no codes are stored for the knock sensors. Which would lead me to believe they are functioning as designed.

Edward :

You ran higher octane fuel and it made no difference at all? didn't make it ANY better?

Customer:

I get the feeling it may be (Dwell).. With the higher octane fuel, it seemed a bit peppyer. Alldo the valve rattle was still there.

Edward :

Right, we don't set the timing on these, it's computer controlled completely.

Edward :

Distributor only goes in one way.

Customer:

ok.

Edward :

I would say first, you want to change your spark plugs, make sure you use factory Volvo plugs in that motor. relatively cheap from the dealer.

Edward :

aftermarket plugs, can cause a spark knock. so double check them.

Edward :

After installing plugs, I would then go to Autozone, see what kind of combustion chamber cleaner they have, There are a few different ones on the market. Sea Foam Redline, etc. Put a couple of bottles of that through the tank. I would not doubt some carbon deposits in the cylinders. And if you get some deposits, they will cause a spark knock. Cleaning the combustion chambers would definitely help it if that was the case.

Customer:

i never knew spark plugs could produce a knock. However i will replace them with Dealer plugs. P.S. this was a 1 family car.It was maintained ( top notch). I normally use LOCUS fuel system cleaner.. Should i change to sea foam?

Customer:

I AM WORKING OFF A PUBLIC LIBRARY P.C. I have 5 minutes time remaining. Can we pick this up from my personal L top.Say in 1 hour?

Edward :

I believe Sea Foam makes a injecotor cleaner, also another product called intake and combustion chamber cleaner. (Can't remember the exact name) Redline makes a product specifically for reducting combustion chamber depsosits. It's a toss up on which really is the best though in my opinion, I would look for a product that specifically said reduces Combustion Chamber deposits and cleans Combustion Chambers though, More so than just a fuel injection cleaner, we used to clean combustion chambers with walnut shells taking the plugs out and had a nozzle that would blast the chambers. I've also sprayed water directly into the engine before while idling, Kind of a steam cleaning effect. When a headgasket blows, you pull the head and the cylinder that is cleanest is the one that had antifreeze in it. So there are a couple of tricks to getting carbon out, but I would use a product specifically for combustion chambers.

Edward :

Yes, let me know if you have any further questions. Thank you.

Customer:

Tnxs, will do

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