71cutlass350

Recently bought a 1971 cutlass s with a 455. The car was repainted 5 years ago and then soon after the guy died and the car has pretty much sat since then. When I bought the car it ran ok but didn't idle great and wouldn't run for very long. Brought the car home and got it to idle by itself, but holy christ does thing smoke. It pour out white smoke with maybe a hint of blue out of the passenger side exhaust only. There was no antifreeze in the oil so I figured it was either stuck rings or a valve problem. I bought some Marvel Mystery Oil and dumped 1qt in the gas, emptied a 1qt of oil and added 1qt of Marvel Mystery Oil to the engine oil, and then while running I poured some down the carb hoping if it was the rings this might break them loose. I let it run for a while and then started revving it up to see if that helped but no luck. After that I shut her down and did a compression test on all the cylinders but #8 because of the damn ac box. #1-160 #2-150 #3-120 #4-160 #5-150 #6-20 #7-130. So obviously #6 was my problem cylinder. Before the night was over i started it up one more time and while running there was a pretty bad clicking noise coming from the passenger side valvetrain but didn't think to much of it. Next day pulled off the passenger side valve cover and wouldn't you know one of #6 cylinders pushrods is so bent i cant even get the damn thing out of the block, all most feels like is bent 45 degrees or more. Im thinking that something was stuck and when i added the marvel oil it broke free when i was revving it hard and bent the pushrod.
My questions are what would cause the pushrod to get bent and would that problem have anything to do with the smoking. Im planning on pulling the intake for sure and maybe the head, what should I look for and what at the very least would need replaced. Sorry for the long winded post but id appreciate the help. Thanks

Fun71

The cylinder filled up with water, which is not compressible. That white smoke you saw was coolant burning due to a leaky head gasket.

oldcutlass

Good theory provided by Kenneth.

Sugar Bear

Agree with Fun71 as to the likely cause. Did any of the spark plugs look steam cleaned or show any corrosion? Can you see the top of the piston, is it steam cleaned?

If this is an auto trans pull the line off the modulator connection at the intake manifold to see if there is any ATF in it from a leaking modulator causing the smoke. That would explain white/blue smoke; but not the bent pushrod or smoke from just one side.

Keep us posted!!!

71cutlass350

Ok just so I'm understanding you correctly the water in the cylinder would have prevented the valve from opening and the extra pressure went to the pushrod causing it too bend? Also I never ruled out a head gasket but with the car running i looked into the radiator fill cap and seen no bubbles coming to the surface resulting in extra pressure in the system from the cylinder. Would that be accurate indicator?

nsnarsk65cutlass

The valve was prevented from opening that is what caused the push rod failure.Coolant-water is not compressible.

71cutlass350

All the plugs looked about the same, black residue and a little moist just figured it was unburnt fuel and the trans vacuum line was the first thing I checked and it was dry. So I might as well just plan on pulling both the intake and the head and replace the pushrod (obviously) and head gasket and hope the pushrod didn't screw up the lifter or cam or anything else.

Sugar Bear

If you can put air in the cylinder with the rockers removed to find the leak/source of low compression before pulling the head it may save some work. This way you would know if the leak is valve related and/or piston/ring related.

About the bent pushrod/cam/lifter damage, the pushrod is the weak link in these situations. A valve may also be bent. The lifter and camshaft will probably be fine.

Keep us posted...

71cutlass350

Ok thanks for the tips maybe I'll see if I can rent a leak down kit from an auto parts store that would be an easy way to get an idea like you said.

Sugar Bear

If you cannot get a leakdown kit, put air in the cylinders using a spark plug air adapter or compression gauge hose, listen and feel for where the air leaks from. A leakdown kit would tell how much leakage there is but at 20 PSI we know it is too much leakage.

71cutlass350

I'm just going to plan on replacing the head gasket and taking a look at the valves and head whiles its off and I'll replace the other sides head gasket at the same time. While I have the heads off would it be worth getting them resurfaced, or if I'm going that far would it be beneficial to even having them milled slightly to make up for the thicker head gasket? Also should I replace anything in the head itself while I have it off so it wont cause me troubles later? Thanks

oldcutlass

You can drop them off at a machine shop and just have them freshened up and with new valve guide seals. There are companies that make a thinner head gaskets, they are quite pricey though.

Sugar Bear

If you can put air in the cylinder first you'll know if there is a ring/piston problem. This could prevent doing a valve/head gasket job, still having low compression due to a ring/piston problem and having to pull the head off again.

Good luck with which way you choose. Fortunately, the problem is most often valve related.

71cutlass350

Good point I'll try that first and go from there and report back. Trying to work on vehicles at home and going to college somewhere else can be a challenge so it might have to wait a week or two but then I plan on tearing into it. Thanks all

71cutlass350

Talked to my local engine builder about rebuilding the heads and he said he thinks the problem was a stuck valve. He quoted me $200 to do both heads and $50 per head to have them milled. I guess my question is am I best off having them rebuilt or just checking them over myself and and save the money if it's not needed? Not sure what a stuck valve all entails so I apologize for my inexperience.

D. Yaros

$300 seems like a reasonable sum to invest to assure that all is in order and provide worry free use.

Fun71

I agree that the bent pushrod and low #6 cylinder pressure was due to a stuck valve, but the real question is why did the valve stick? Did it bend due to a head gasket leak/cylinder full of water? Or was it something else?

oldcutlass

It could have had a lot of carbon and ? buildup on the valve stem.

Fun71

Yep, there could be many causes. I'm just circling back to the dense white smoke that was reported pouring out the passengers side exhaust.

redoldsman

That seems like a good price on the heads. I would get them done and when I got it all back together, I would have somebody crank it over with the plugs out and make sure all the valve are opening and closing.

71cutlass350

Well while I have it all disassembled I might as well have the heads gone through so I dont have any future problems. Whatever the problem was hopefully this will fix it.

oldcutlass

Are there any marks on the top of the piston/s?

71cutlass350

Haven't been able to check that. Should I be worrying about a dropped valve?

oldcutlass

I would check, just look at the top of the pistons where they are.

Firewalker

For future reference usually stuck rings can be made ok with a small amount of Mystery Oil through the spark plug holes and put plugs back in, and then let it sit for a few days or weeks. You still should have most of the quart left.

71cutlass350

So I was able to get it all torn down this weekend. The engine looks to be all original and probably never even disassembled, still had the factory head-gaskets and turkey tray intake gasket. Turns out pushrods were bent in cylinders 6 and 8 and I suspect if I would have been able to get the compression tester on 8 it would have been low too and that would make sense with the blown head-gasket theory. I will attach pictures of the heads and I want your guys opinion on how bad they look, hopefully they don't end up costing me an arm and a leg but at this point I might as well get the problem fixed. Also on #6 cylinder the lifter that was for the bent pushrod seems to have suffered some damage. Do I need all new lifters or can i just buy one? On the plus side the the pistons have no marks and cylinder bores are all smooth.

Sugar Bear

Yes you can replace lifters one at a time. Check all of the pushrods by rolling them on a flat surface e.g., a piece of glass and examine the rocker arms closely on the rods that are bent.

Looks like head gasket was leaking between #6 and #8, the sealing line between them was breached.

How bad do the heads look? Really cannot tell much until they are disassembled.

Good luck...keep the thread going to completion!!!

Fun71

Yeah, those chambers look as if they were steam cleaned with antifreeze.

71cutlass350

Heads will be dropped off tomorrow morning and in the mean time I'm just making sure I have all the necessary parts lined up. I'm going to be getting new exhaust manifold bolts and rather than buy some overpriced bolts online would I be ok getting some grade 8 bolts from fastenal? Also I have a set of intake gaskets at home but should i be using the factory style valley pan instead?

oldcutlass

You can use GR8 bolts. I would use the valley pan intake gasket. I would pull all the lifters and inspect the bottoms for wear, they usually get concave. Make sure if you are going to reuse they go back into the holes they came out of. While the lifters are out also inspect the cam lobes for wear especially the one with the bad lifter.

Sugar Bear

Not because of the bent pushrods, but since you are doing a valve job and essentially freshening up the top half of the engine, have you checked the condition of the timing chain and gears or considered replacing them? If they are worn now is the time...

Good luck!!!

Ozzie

Try to do an accurate diagnosis of the mechanism of failure and which components have been damaged. You only need to do replacement/refurbishment of those components needed to bring everything back to within specifications. If a lifter is damaged that lifter should be replaced. The good ones do not need to be replaced. Keep in mind that all lifters were not all the same diameters. The head should be thoroughly checked while it is off. It should be checked for cracks, warping, pitting or gouging of the sealing surface, etc. The valves, their seats, and their guides should be inspected thoroughly. If a valve stuck it's problem should be resolved. If the head is straight and nothing else is amiss with the sealing surface milling is unnecessary. Your photos indicate a relatively clean engine which makes me think that regular maintenance was performed. Let us know how you are doing.

71cutlass350

This is my first time tearing into an engine so I really appreciate all of your guys help and advice, it helps me out a lot.

oldscutlass I'll make sure to order a valley pan gasket and I'll check over all the lifters.

Sugar Bear I have briefly thought about the timing chain but because this is really just a side project that i plan on selling eventually i want to keep it as cheap as possible but I understand the benefit of doing it now while its already torn apart. How difficult is a timing chain to inspect or replace and if i do inspect it what parts should i look at for wear?

Ozzie Are I had the understanding all the lifters in the 455 were .842 or am I misunderstanding you. Also the machine shop will thoroughly be check over my heads and they will let me know of any problems.

Question for anyone, whats the best way to remove the lifters? I tried very quickly to pull out the damaged one but wouldn't budge, any specific way or tools or do they just slide in and out?

olds 307 and 403

Look for flaked off plastic on the cam gear if it is the stock timing chain. Also check chain slackness. The timing cover is challenging to get on with the oil pan in place. The lifter should pull out, there may be sludge and varnish holding it in place. Push it up as high as possible, use pliers or vice grips, twist and pull.

Sugar Bear

If the engine had original head gaskets and looks as if had never been apart then it is quite likely the timing chain and gears need to be done. The main problem is that the factory camshaft gear had nylon teeth and fail from, age, heat and stress. If it jumps time it might bend valves, probably won't but might. A worn chain and sprockets also retard the valve/camshaft timing and the nylon breaking off the camshaft can clog the oil pump pick-up screen. It is a labor intensive job, conservatively four hours for someone used to doing them. As far as technical difficulty not very, read-up on the procedures until you understand them if you choose to do it. You seem to have tackled this part well, you could do the chain and gears by reading and posting questions on the forum.

Ozzie

Generally all the lifters are the same diameter, however during production there were occasions where it was found to be advantageous to use an oversize lifter. The oversize lifters (if used) were 0.010" oversize. These were marked with an "O" on the lifter's boss, visible from the top. The "approved" removal tool was designated BT-6407, provided by the Borroughs Tool Company. It "grabbed" the lifter from the top and extracted it with a twisting and pulling motion. You can see it in the chassis service manual. This exact tool will probably be difficult to find. Substitutes can usually get the job done.
As has been said, the original cam gear can cause significant problems when they fail in service. This type of gear was also used by other manufacturers beside Oldsmobile. I recently changed one in a Ford engine. To me it was a sad compromise. Replacement with an all metal gear is a good investment if you plan to use the vehicle.

oldcutlass

I've used pliers, dental hooks, etc for removing lifters. Use pentrating oil to dissolve varnish buildup on the bottoms of the lifters. Be careful if the bottom of the lifter is very worn and concave it may have mushroomed out and may damage lifter bores.

Sugar Bear

X2 oldcutlass.

Dissolve gum and varnish first but if the bottom of the lifter is mushroomed using a lot of force to get it out can damage the lifter bore. When lifters are really stuck they can be taken out by removing the camshaft and pushing them downward. If you have the oil pan off just let them fall, if not removing the pan cut a cardboard tube like the one camshafts come in lengthwise, slide it in where the camshaft was and it will catch the lifters.

71cutlass350

Might as well do the timing chain then for the extra $60-$80 it costs me then and have that piece of mind. Now I'm thinking by the time I buy new lifters and have the timing chain off and replaced, how much more is it just to replace the cam and would you recommend replacing it? These MAW's will get you every time but I guess now is the time to do it.

Sugar Bear

If the cam looks good and you are satisfied with the performance I would not change it. If shows a problem/wear or you want more performance then yes I would change it.

Are you replacing all the lifters or just the bad ones? Lifters that are not worn can be disassembled and cleaned, however it is time consuming.