Got a weird one here, maybe. I was out tuning the B20 I'd just swapped into a Volvo Amazon, when suddenly the engine lost power and started smoking profusely. It was very sudden, like a switch had flipped, and happened while I was revving the engine in neutral.
I checked the plugs, and #1 and #2 had oil on them.
I checked compression, has >120 psi in cylinders 2, 3, and 4, but zero in cylinder #1
I pulled the valve cover, and noticed that the pushrod for the #1 intake was not touching the adjuster on the rocker arm. When I cranked the engine, the pushrods all went up and down, but the pushrod for the #1 intake would not touch the rocker arm.
I pulled the pushrod, and compared it to a known good used one, and it looked identical. The rocker arm does not appear to be damaged, and the adjuster was in place.
This engine (1975 B20) uses solid lifters, so it wouldn't be a collapsed lifter.
It feels like a collapsed lifter, though. The pushrod on the #1 intake does go up and down, and by eye it looks like about the same amount as the others do. It's just like 1/2" too "short", if that makes any sense.
Maybe the lifter suddenly broke somehow?
Bent valve hanging open will do that as well. Take a look at the valve height wrt other closed valves. Should be pretty obvious.
I have seen solid bucket lifters develop holes in them, a pushrod may be able to punch through one depending on the design. Also could be a bent pushrod.
Paul_VR6 (Forum Supporter) said:
Bent valve hanging open will do that as well. Take a look at the valve height wrt other closed valves. Should be pretty obvious.
I have seen solid bucket lifters develop holes in them, a pushrod may be able to punch through one depending on the design. Also could be a bent pushrod.
The valve looks OK. I put a spring compressor on it and with the valve spring compressed the valve goes up and down freely.
The pushrod was straight and true, rolled it on a table.
Punching through the bucket on the lifter sounds like a possibility. I'm going to yank the head tonight. Best case scenario, a new set of lifters and pushrods.
Zero compression is a good sign that the valve is not fully closed.
paddygarcia said:
Zero compression is a good sign that the valve is not fully closed.
The exhaust valve opens and shuts freely. If the intake is closed all the time, it can squeeze, but it can't really suck anything to squeeze, so compression would be pretty minimal.
Quick leakdown test will tell you pretty quick.
Camshaft lobe failure was common on B18 and B20 engines when they were relatively new. I replaced probably 35 of them between 1968 and 1986 
This was with old high zinc oil too. Some had been poorly maintained I am sure, but at least two of them were regular customers who always did routine service on schedule.
tuna55
MegaDork
7/26/22 12:23 p.m.
TurnerX19 said:
Camshaft lobe failure was common on B18 and B20 engines when they were relatively new. I replaced probably 35 of them between 1968 and 1986 This was with old high zinc oil too. Some had been poorly maintained I am sure, but at least two of them were regular customers who always did routine service on schedule.
Sounds indeed like the cam isn't.
TurnerX19 said:
Camshaft lobe failure was common on B18 and B20 engines when they were relatively new. I replaced probably 35 of them between 1968 and 1986 This was with old high zinc oil too. Some had been poorly maintained I am sure, but at least two of them were regular customers who always did routine service on schedule.
I've heard a lot about this, too. But would a cam lobe fail suddenly? Also, the #1 intake pushrod still goes up and down, just at a significantly lower altitude than the other 7. So it doesn't seem likely that its the cam.
EDIT: Of course, if a lifter took out a cam lobe in its self-destructive episode, then I may be doing that, too. Will inspect the lobes for wear, scoring, or other damage while it's apart.
volvoclearinghouse said:
Paul_VR6 (Forum Supporter) said:
Bent valve hanging open will do that as well. Take a look at the valve height wrt other closed valves. Should be pretty obvious.
I have seen solid bucket lifters develop holes in them, a pushrod may be able to punch through one depending on the design. Also could be a bent pushrod.
The valve looks OK. I put a spring compressor on it and with the valve spring compressed the valve goes up and down freely.
The pushrod was straight and true, rolled it on a table.
Punching through the bucket on the lifter sounds like a possibility. I'm going to yank the head tonight. Best case scenario, a new set of lifters and pushrods.
It sounds like this is not your problem, but the goal is to remove all of the rockers and run a straightedge across all of the valve tips. One too low or too high indicates bent valve or other issues.
Wow! That is one worn lifter. Was it not getting oil?
That does look problematic.
I knew the answer at the title...
42 years working on Volvos.
Edit: You know to not use an impact wrench to install the nut holding the timing gear on, right?
Miraculously, the cam lobes look OK. I have a new lifter + pushrod set, waiting on some gaskets, which should be here tomorrow, to get everything all bolted back together.
Streetwiseguy said:
I knew the answer at the title...
42 years working on Volvos.
Edit: You know to not use an impact wrench to install the nut holding the timing gear on, right?
I posted this on a Volvo Amazon FB group that I'm on, which has members all over the world, and so far have had two gentlemen who claimed to have decades of experience working on Volvos say they have never seen a lifter do this. It appears to be a factory lifter, too.
In reply to volvoclearinghouse :
A lifter failure is pretty common. A lifter breaking is not, at all. Where is the bottom portion of it? Did it just break in half, or shatter, or wear away and then break the bottom off?
They normally wear concave, then carve the lobe off. Occasionally, they carve all the way through the cam and the crank shoves them out the side of the block...
In reply to Streetwiseguy :
I lifted the engine up, and managed to sneak the oil pan out the bottom of the car. The rest of the lifter bits were down there. Many of the rocker arm adjusters were pretty far down, so I suspect when I start pulling the rest of the lifters I'm going to see some...interesting...things.
In reply to volvoclearinghouse :
Adjusters are threaded way down, or threaded way up? Way down could be lifters, threaded way up could be recesses valve seats.
Yikes - 50 years experience working on cars (including Volvo's) never saw a lifter break like that......
The other 7 lifters were in widely varying states of decay.
The height varied quite a lot. #1 lifter is on the left.
The lifters wouldn't extract from the block easily, so I fabricated this tool that slips over the lip in the tip of the lifter, and used a slide hammer to pop them out.
WOW , with all the junk running thru the oil , how are the main bearings etc ?
Wow, that is impressive. And not in a good way.
Cam time! This will be fun.
Go for a 3/4 race cam! 
Scott
