Sirlancelot
Backfiring through inlet and exhaust
Good day guys! I have a Pajero 3.5 v6 24 valve,6G74 engine. I had to remove the cylinder heads to do valves due to burnt valve on no 4. After replacing all the valves due to very high mileage over 340000kms due to the seats also worn quite thin they re seated the valves and tested for leakage which was ok. I fitted back the heads and tried starting the vehicle which now back fires and shoots flames through the inlet and exhaust. I took the heads back and they saw the valves where stuck open and took off the necc milimeters to compensate. After collapsing the hydraulic lifters we fitted it back and it just keeps backfiring through the inlet manifold. Has anyone experienced such a thing before and I was also told that the cylinders on this engine is not like any other v6 but number 1 is near the battery ( R/H ) and 2,4,6,is left hand is this true and what exactly is the firing order? I have tried everything in the book that I know being an Audi Technician for 30 years this has me stumped.

Please I would appreciate any feedback if possible.
Re: Backfiring through inlet and exhaust
Got to be incorrect valve timing. Check the forum under Technical Spec somewhere? There is lots of info there.
trekker1
Re: Backfiring through inlet and exhaust
You need to be dead certain of which cylinder is No.1.

I think it is the front of the engine on the RHS when facing the engine from the front of the truck.
Aucamp
Re: Backfiring through inlet and exhaust
You could have switch the 2 camshafts. Go back to basics with a dell stick in piston no. 1, rotate the motor clockwise and check the opening and closing of the valves for the 4 different strokes.
Re: Backfiring through inlet and exhaust
2 or 4 camshaft engine. No1 is right bank front(closest to air filter) 1-6 from front to back, firing order I 1,2,3,4,5,6. Do you have the workshop manuals?

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