Any years Dead cylinders

[KC Tom]

My 322 LaSalle has started idling very rough and losing power. After I get up to speed it seams to cruise ok.
I did the old pull one plug wire at a time to find dead cylinders and discovered that two adjacent cylinders make no difference when I pull plug wires. Did a spark test and both are getting strong spark. I can't seem to find my compression tester so will buy another today. Suspect head gasket but not sure. If so how difficult is it to change one?
Any advice on anything else to look at?

[KC Tom]

Just did a compression test and number 2 and 4 cylinders have zero compression. Looks like time to pull that head and replace gasket.
Has anyone on here ever replace s head gasket on a Lasalle and have any advice ?

[V63]

"If" the vehicle was run on STALE fuel it causes the valves to seize in the guides which leads to no compression.

[KC Tom]

Ok
How do you fix that

[V63]

They can be give the illusion that they are  'welded' in
Place ...yes,  very well  seized.

on an OHV engine, head removed  I soaked it in lacquer thinner for a few days, then lye bath.

ultimately sent to head shop for finalizing.

[KC Tom]

Unfortunately this is a flathead so have to fix myself as don't want to pull motor. I will remove head and see what's up.

[V63]

Unfortunately this is a flathead so have to fix myself as don't want to pull motor. I will remove head and see what's up.

Yes, I do understand that complication.

[Bob Kielar]

I have no knowledge of flathead engines other than they look cool. I used a borescope on my 331 to see if the valves were moving. I put the scope in the spark plug hole and noticed the valve location removed scope bumped engine then looked again to see if they moved. When I purchased the scope I was hesitant but I have used it a lot for various projects both auto and home. Just a thought.

Regards,
Bob

[Chopper1942]

You know you have an issue with two adjacent cylinders, so it is probably a piece of the head gasket has burned out between the two cylinders. Remove the cyl head. Clean the cyl head and block with a scraper. A carbide scraper works best. Don't push it like a normal scraper, pull it towards you. It will clean the surface and not scar the surface. Do not use a whisk wheel or abrasive pad in a drill. They can cause an irregular surface that can be a leak source.

Get a long and a short straight edge. Check the length of the head at several places and then across the head in several places. Especially where the gasket is blown out. Check OEM spec. A rule of thumb is: No more than 0.001" per cyl on the bank. On yours, this would be 0.004" for the length of the head and block. Across the head or block 0.001".

Torque the head bolts to specs (70-75 lbft.) and in the proper sequence. Make multiple passes. 20, 40, 60, then 75 lbft.  Put some miles on the engine and then with the engine cold, retorque the head bolts.

If it does happen to be valves stuck, rotate the engine by hand and see if they open and close on the two cylinders. If they are sticking, you can spray some PB blaster, GM Rust/Penatrating oil (used to be called GM Heat Trap lube) into the ports and on the valve stems.  Let set for a day, while respraying the valves. Rotate the engine by hand until the affected cylinders are each at TDC. Take a soft faced hammer and lightly tap the stuck valve.

for example: If #2 cyl exhaust valve is stuck, rotate the engine until #2 is at TDC after the intake valve opens and closes, this is TDC compression amd the exhaust valve should be closed. Tap on the open exhaust valve with the soft faced hammer or put a punch in the center of the valve and tap on the punch with a ball peen hammer. The valve should snap shut. Do the same to cyl #4.

If an intake valve is stuck, rotate the engine until the exhaust valve just starts to open. The intake valve should be closed at this point. Tap on the center of the intake valve until it snaps shut.

Once the valves are unstuck, rotate the engine by hand until each valve is open and squirt light oil into the ports onto the valve stems and the rotate the engine several times while watching the valves to make sure they are closing.

[KC Tom]

Thank you for the very thorough response. Because it has effected adjacent cylinders I am guessing that it is a gasket. Odds against stuck valves being adjacent but stranger things have happened.
Just started removing head bolts and most are coming out fairly easily but of course a few are fighting me.

[KC Tom]

Any suggestions for loosening up stubborn head bolts? Have used hammer and brass punch and sprayed with pb blaster but won't budge even with cheater bar

[V63]

Maybe graduate to heating the bolt? might help your lubricants penetrate.

I might try an impact but of coarse always a risk of breaking the fastener, but one or two of that would not be tragic on a flat head in most locations.

[Chopper1942]

Get some sticks of bees wax. Heat the head of the bolt until its is red. Touch the bees wax to the bolt and let it wick down around it. Do this several times. Usually, on L head engines, the bolts would be stuck to the head and not in the threads.

I've broken more bolts by hand than with an impact. If you use an impact, just rattle the bolt a few times, don't hammer it real hard or you may break it off. An impact driver can also work, if you don't have a 1/2" impact.

After you have used the bees wax several times, heat the bolt and put some more bees wax on the bolt and while still hot try to loosen the bolt. Just be careful. If you are doing this with a breaker bar, if/when you start to feel like it is moving. stop and try to back it up. If it starts to move more easily, then continue to remove the bolt.

If you get it out in one piece, discard it and get a new bolt. The heat will have changed the metallurgy of the bolt and it will not stretch properly when you torque it down.

[KC Tom]

Thanks again for the suggestions

[KC Tom]

I have been slowly getting the head bolts off. Just 3 left and have only broken one.as hard as they are to get off I would like to replace them all but can't find anybody who has them. Any ideas where I might find them? Also will need gasket.

[KC Tom]

Got the head off and there is a 2 inch or so in the gasket between the two cylinders that are dead. Wonder what causes that.

[James Landi]

"Wonder what causes that."

You've asked EXACTLY the most important question.  Suggest that you re-read Chopper 1942.  Here's my take: In some cases, there's  a spot of intense heat between the cylinders--- a chunk of rust or gunk restricting the flow of coolant at exactly the place(s) where heat from combustion is most intense, so the gasket melts and burns.  Also, ignition might be slightly off, creating excessive heat under load. What is the statis of your radiator--- if it's partly clogged, summer ambient heat can create damaging hot spots.  (Often, using an infrared thermometer will uncover hot spots that don't show up in the coolant temperature. gauge)  My suggestions:  make certain that a machine shop magna-fluxes the heads (for cracks --- they're not uncommon, especially in a situation like yours) have the shop check for warping, and you must check for warping of the engine block deck, and while you have the engine apart, blast fresh water down the water jackets to remove accumulations. Hope this helps, James

[KC Tom]

After careful inspection I discovered a very small crack in the head. The machine shop cleaned the head up and tested for any other issues and found none. Head is now at trusted welding shop and when completed I will take back to have decked.

[V63]

I fixed a 365 cracked head once as a 'cold weld stitch",
it's a process of drilling a hole at end of crack, tapping it and threading a plug into it. Grind it down flush then drill another hole that overlaps the prior plug by 1/2.