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Good Evening Everyone, have not posted here in a while. I have a 1965 Volvo 122s withy a 1974 B20, fuel injected head with weber carb. Just completed a rebuild with new bearings, piston rings, etc. Reason for rebuild is due to no compression on number 3 cylinder. Prior to rebuild, I tried a carbureted cylinder head just to make sure it was not the FI Cylinder head. Same issue, no compression on number 3 cylinder. So I went ahead and did the rebuild. Put everything back together and I'm back to same issue, no compression on number 3 cylinder. I cannot figure out what the issue is. Put air through the sparkplug holes and it will move the crank on all cylinders, but when I do a compression test, nothing. I just can't think that both cylinder heads will have the valve's bent or similar issue. I tested the carbureted cylinder head by putting water on the intake/exhaust port holes and the valves appear tight as nothing is leaking. Not sure if the FI cylinder head may have a bent valve, but as I said earlier, I would not think both cylinder heads will have the same bent valve or similar issue. If anyone has any ideas, please post here. Thank you so much.
1965 122s
1991 740T SE with cracked back glass - looking for one
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Assume that you have ruled out bad head gasket?
dean
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Hi Dean, yes, head gasket was intact, no signs of antifreeze or anything out of the ordinary. I'm still trying to see if I can put the carbureted cylinder head instead of the FI one. A little story behind this rebuild. This engine/car had been running fine, with no problems whatsoever. I found a Turbo set up, intake manifold, weber carb and turbo. I was able to set up the turbo but after a couple of tries, I decided to put that to the side. The engine ran with the turbo but I was not able to drive the car. Not sure if this is what caused the problem I'm having now. Once I put everything back together, that is when I had the issue with no compression on number 3. I changed the FI cylinder head to the carbureted one and did the same thing, no compression on number 3. This is when I found there was antifreeze in the oil pan. Since I found antifreeze in the oil pan, I figured to have blown the head gasket while running the turbo. Decided to do a rebuild, new piston rings, bearings, new head gasket for the FI cylinder head, etc. When I put the engine back together, the cam lobes appeared fine, although I did not thoroughly inspect them, everything "appeared" intact. Nothing broken, just the head gasket seemed to have leaked antifreeze into the oil pan.
I'll see if the carbureted Cylinder Head works and come back here to post the results. If it works, I suspect is a valve or valve spring. I wanted to use the FI cylinder head as the car feels has more power with it.
Thank you everyone for all the input.
Luis
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Before you change heads again, perform a leakdown test on cylinder #3.
I believe you can get a loaner leakdown tester from Autozone.
You will need access to an air compressor.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com
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Good Afternoon Everyone,
Just finish running the engine with the carbureted cylinder head. There is compression (90 lbs) on number 3. I also put gas on both the intake/exhaust port of the FI cylinder head number 3 cylinder, to see if it would leak out. Id did, on the exhaust port. However, is leaking through the top of the valve spring, maybe the valve guide is lose, Now, the car runs but cylinder number 3 I'm only getting like 90 lbs compression with the carbureted cylinder head. Rest of the cylinders is in the 120+ lbs compression. Will keep digging into this. Thinking I need to put new valve guides on the cylinder head (FI) one. Hopefully it will work.
Thank you for all the input.
Luis
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If gas is seeping from the up-side-down cylinder head combustion chamber you have a problem with the seat, the valve or both. I would think the gas at the top end of the valve spring is just the thin liquid following a path past the valve head and continuing down the stem. Valve guide to valve stem clearance may be small but's not zero. With the valve out to deal with it's problem, put it mostly back in and give it a wiggle.-If you can't feel side to side movement it's OK. If it does have play it wont be the only one. But valve guide play will result in oil consumption--not loss of compression. - Dave
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I think you have had the same low compression with both heads on the same cylinder so unlikely to be the head. A big coincidence if it was. 120 compression is low. 160-180 better. 10% difference between cylinder acceptable. New rings won't have bedded in yet so that won't help compression. Did the bores get honed for the new rings? Glazed bores are generally not fixable without honing.
Did you use the same rocker gear with both heads? A cam can be checked visually for excessive wear by watching the rocker movement while turning the crank by hand. A dial gauge on a magnetic base is obviously better if one is available.
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If you found anti freeze in the oil pan your turbo experiment could have cracked the bore on #3, especially as you were using a high C.R.
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Has it run since the rebuild? OK it will sound like a sort of 3 cylinder and if it has a flat cam lobe it will still run. If it does run, do so with the rocker cover off and see if the valves/rocker function normally on #3. It will splash oil so add a couple of bits of cardboard to catch it. Cloths can catch the fan and belt so be VERY careful if you use those.
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Hi,
I agree with your perspective of diagnosing the rocker arms.
A low cam lobe will show up when comparing each of number three rockers with the adjacent cylinders for movement.
I would turn it all by hand and use a dial indicator to view the results.
If a cam has gone flat there may be more than one or a set of them that didn’t heat treat correctly.
This is why I asked if this was a push rod engine.
When setting the lash clearance it’s easy enough to remove all the low spot needed to close valves.
What I have a problem with is this. Why aren’t the valves closing entirely? Those lobes would have to be nearly round or the lash was set entirely wrong somehow. Even each time must be a clue?
There should be specs of rise and fall with degrees of rotation to clear the cam of any wrong doing.
There is some duration overlap in all of this so the dial indicator and a degree wheel will definitely find a problem, if it is a mechanical one?
There some truth around where he said that switching the head and valve sets within them still came up with number three being or having the same issue.
The wrong head gasket to either head is one I can agree with very easily. Especially in relation to the engines cooling jackets and oil drain passages.
With a carbureted head or having injectors signifying there are head differences would have me suspicious right off the bat of what history this engine has.
I just don’t know anything about these older Volvo engines so I got to stop speculating in that area.
Like I said I’m interested to any conclusions to resolve the thread.
Phil
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Good Afternoon Everyone:
Removed the cylinder head and all appears fine. No bent valves,piston looked intact, no antifreeze in oil. Prior to the rebuild there was antifreeze in the oil, hence the rebuild. All looks fine, I'm puzzled about this. I'm about to put the carbureted head and see if it does the same. In the mean time, to answer some of your questions, this is a B20 with the cam on the side. All rocker arms, push rods appear fine as well. I removed the valve cover while engine was running as someone had suggested and they all move up and down, however, I don't know to what degree. They all seem to be moving up and down the same across all valves.
I'm going to try and put the carbureted cylinder head this weekend and come back and let you know what happens. I'm on my third headgasket with this build. Will be re-using the last one as it appears to be ok.
Thank you all for your input.
Luis
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Before you install the B18 head -- set it up on a workbench upside down. Carefully pour gasoline into each combustion chamber. If the valves seal properly you will not see any gas at the intake or exhaust ports. I've been following this thread and even with 48 years experience with the B18/20 I am totally baffled. Are you sure you have the procedure for setting the cam timing relative to the crankshaft? Dots on the timing gear and crankshaft gear facing each other---which BTW, is TDC compression stroke for cylinder #4 (closest to the flywheel)-- Dave
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Hi Dave,
Hey Dave I think you may have named a very plausible reason for our baffling moments.
I gave you a thumbs up!
The idea of timing the cam off of a number one cylinder instead of the number four, when it required that way, sure could explain a few things.
It would be like setting the ignition timing on a V-8 on one corner of FORD engine when it’s a CHEVROLET engine that one’s number one on the opposite front corner.
So is it possible to have the camshaft is 180 degrees out of sync.
But would look right by the dots mechanically and still run?
I say yes, apparently?
We know that a four cylinder engine has two pistons traveling together with the ends up and then the centers follow.
A 360 degrees of rotation is divided by four cylinders means they are 90 degrees apart.
The pistons don’t care when they compress or just are flowing gases.
The cam only closes both valves on each cylinder one at a time completely for compression.
The rest of the time there are open valves someplace as valve overlapping is done to increase time to scavenge or charge.
Now this is getting deep for a boy that likes swimming on a shallow end. 😎
I suppose there could be a problem, that accumulates, to end up with only one cylinder but why? I’m baffled too.
This number three thing alone is beyond my thinking, without a lot of specifics about the cam.
It’s right there, when my brain fogs! 😵💫
He might have to spin the cam one-half a turn before this is over.
Then again why or for what ever reason, did they decide to time the ignition onto the back or rear cylinder?
Does the rotor point to number four or number one under the cap?
Did the Saab Co. have something to do with this engine? 🤔
The engine of those cars do look to be in backwards along with the hoods.
I heard that the ignition key was down in between the seats. 🤨
I bet the tumblers get grungy inside. 👀
The V-8 engine above have two banks but appears that the game was still played the same way. Because they can!
So the ends or the two middles spin to counter forces of balance to cancel each other across the block vertical halfway or at 45 degrees.
The firing orders are the same but across from each other that makes the power pulses more divided so the engine runs smoother at idle.
Let’s not forget the Wankel rotary engine on the other end of the spectrum.
A four banger inherently shakes during shut downs without the Mass of half of another engine.
Other countries have used ten and twelve cylinders with variations of smoothness.
We have learned the V-8 and V-6 have less of a weight penalty as more rods and pistons a crankshaft.
I have realized over the years that a mass spinning creates more torque kinetic inertia and stamina.
Flywheels are considered to be in the mix for fuel cell/electrified vehicles.
In a recent visit to the Dearborn, Michigan Ford museum and seeing a massive locomotive used to move coal on the eastern seaboard was an astonishment.
I rode some even bigger machines around a big parts in my day.
Just like our ancestors except my working conditions got a whole lot better.
They were a dam tough generation!
Cranes or air pads moved my parts.
So I realized what kind of massive machine it was in the forties.
All while Doing 60 mph per hour near empty on two little rails or while pulling 160/ 60 ton cars slowly cost a lot of energy.
The coal tender used what looked like a 14” diameter auger screw to feed the boiler.
I Didn’t get any statistics on a water tank, while there, but it was bigger than my lunch thermos. 🤪
FYI, it’s worth going here but plan a couple days or more if you read.
https://www.thehenryford.org/collections-and-research/digital-resources/popular-topics/allegheny-locomotive/
Phil
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Hi,
My first thought was or if are you using the same cam over to either head?
I’m a 240 overhead cam guy myself so you see why my first thought could be valid especially if you get the shimming wrong way way off.
I have to say this is a very unique test result and want to say the common thread might be a possible “operator error.” At my age I have found that door left unlocked more than once.
Aren’t those engines a push rod engine?
I have no idea when fuel injection started either so the head swaps is exactly that way over my head! 🙄
1965 is pretty far back there. I think the Bendix Co. during the 50’s did experimental for aircraft and “hot rods” were abound.
In the sixties that work was sold off to the Bosch family. It was probably a collaboration to begin with.
Back then, if any devices running it would have actually fill up the back seat.
Like alternators were the newest thing in production.
Maybe you have a very flat cam lobe or or it’s way out of time.
Surely you would have seen wear it unless you left the engine in the car? On V-8’s the cams and hydraulic lifters is another ball of wax.
The latter about timing wouldn’t necessarily work with the other cylinders coming up in compression.
Even if a compression ring went in upside down it would still have some pressure as compression rings use pressure to expand themselves. The little bevel is important.
I don’t have any other ideas unless the engine was rebuilt before you by someone in the East Tennessee Area.
I from that state originally and was asked, while I was in the Navy, if I was a ridge runner?
I didn’t know what that person was asking.
He explained, that if so I would have one leg shorter than another.
I said no, I was from the west side of Central Tennessee. But I never forgot that one.
I never moved back to Tennessee either. Thanks partly to its stigma and the south in general.
So with that, did you compare the rods for length?
A 1/4 inch or less would make a big difference. 👀🙃
A Piston heads top or crown to the wrist pin height is another one. You gotta appreciate the hot rod people of that era. They became the muscle car engineers for the big three.
If I went way back to the days of “top hats” I bet there’s a joke in there somewhere too. 🤪
Lets us know what you find as I’m interested.
Phil
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