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Dave Nova
Dave Nova, Buick Technician
Category: Buick
Satisfied Customers: 1808
Experience:  ASE Master Certification. GM World Class Certification
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Buick century: 95 buick century had bent intake valves,replaced

Customer Question

95 buick century had bent intake valves,replaced them car ran for about thirty minutes and bent valves again,but only the intakes.
Submitted: 7 months ago.
Category: Buick
Expert:  Tracer replied 7 months ago.
Hello, what engine do you have?
Customer: replied 7 months ago.
2.2
Expert:  Tracer replied 7 months ago.
the V6 engine has different size pushrods, the 2.2 does not, I am unsure on this problem so I will opt out and open the post to the other experts, one should be along soon to help
Expert:  Gary replied 7 months ago.
Hi there,Clearly the intake camshaft is not time correctly, most likely has slipped under the cam sprocket.Did you, or the head shop pull the cams out?Gary
Customer: replied 7 months ago.
This engine has never been apart before and I believe it only has one cam. The engine was running fine before someone pulled the wire harness from underneath and ripped the wires and I had to replace the wire harness.
Customer: replied 7 months ago.
This engine has a timing chain not a belt as I have pulled the timing cover and the cam crank gears are both lined up.My question also is if the timing was off wouldn't the engine not start and wouldn't it miss if it did?
Expert:  Gary replied 7 months ago.
This is an early pushrod engine.About the only the reason I could see bending all of the intake valves would be is if the camshaft has excessive endfloat.Have you still got the timing cover off?Are the all the valve springs fitted the correct way, close coils to the head?I can't imagine what could cause it to be fine until you replaced the engine harness.Gary
Customer: replied 7 months ago.
That's whats got too the car belonged to my parents and they didn't drive for the last few years before they passed away. The car has only 127000 on it.I had driven the car the week prior to the wires being ripped and it ran perfect.I towed it to my home town and replaced the harness.the car started up and ran fine for a little while and I turned it off.When I went to start it back up it backed fired and wouldn't start anymore just cranked fast like out time or no compression.I replaced the intake valves and the car started right up again and ran fine until it just started idling lower and lower than died and just cranked fast again.I've been working on cars most my life and never have I seen this before.Usually if it's out time it won't start or it'll miss or back fire when you crank it.
Expert:  Gary replied 7 months ago.
Ok, were the valves bent when the head came off?Will it run ok for a while once the engine has cooled off?I had a Customers car (Daewoo Lanos) a few years back that would not start no compression.160,80,40,0, then 0,0,0,0. But any cylinder first would be 160.Ending up being the lash adjusters holding the valves open from excessive engine oil pressure.Oil flush with 3 litres kerosene, 5 minutes, oil flush with ATF, 5 minutes, 6 oil filters etc.Backfire is certainly a sign of valves still open, since the fuel and ignition timing are obviously still correct.Your thoughts?Gary
Customer: replied 7 months ago.
I have't pulled the head a second time yet,but have the same thing happening again.The engine will not start anymore as there is absolutely no compression.There is no adjustment on this valves.
Expert:  Gary replied 7 months ago.
Did all the inlet valves kiss the pistons and then bend, hence no compression?How bad were the marks on the pistons?Is this a hydraulic cam, and are the pushrods all the same length?Gary
Customer: replied 7 months ago.
There really wasn't that big a mark on the pistons and the valves were bent enough to keep them from closing I'm not real sure,but I think one was almost closed, just bent to one side enough where there was no compression.
Customer: replied 7 months ago.
I had to cut the stems on the top side of the valve guides to remove the valves.
Customer: replied 7 months ago.
You asked about the timing chain and gears,well the chain was still tight not much wear on the gears,and the rail guides were still in good shape not much wear there either.
Expert:  Gary replied 7 months ago.
Ok, that's good about the chain and guides.I would take the cam gear off to see if the locating dowel has sheared off.There is nothing else to say why are the inlet valves would be bent.A quick check would be to see if the valves on cylinder 4 on overlap are the open by the same amount when cylinder 1 is on compression and vice versa.Something in timing has shifted, and so the inlets are open too far as the piston chases them towards TDC.Gary
Customer: replied 7 months ago.
Could the lifters cause this to happen.
Customer: replied 7 months ago.
If the cam locating dowel would have sheared would it have started after I replace the head ? Why didn't it bent the valves right away when I started it?
Customer: replied 7 months ago.
I know that i'm asking a lot of questions,this has me buffaloed,only because the car was running fine before the wires being ripped.
Expert:  Gary replied 7 months ago.
Yes, it is certainly a strange problem you have there.I wish I was with you to see it with you.Are you about to take the rocker cover off again?Yes the lifters could cause it. I would check the oil pressure cranking.The one I mentioned above had a stuck relief valve and 120 psi cranking.Gary
Customer: replied 7 months ago.
I will let you know what Ii find as soon as I do
Expert:  Gary replied 7 months ago.
Ok, it does sound like a one off type fault.I'm here for you.Gary
Expert:  Gary replied 7 months ago.
Hello again,How are you going with your problem?Gary

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