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240 Compression results 210/55/86/115 guess head gasket job didn't work

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petebee

Member
Joined
Sep 13, 2012
Location
Back in NC again...
Sorry to post another thread about this, but these test results of 210/55/86/115 seem odd. They definitely point to user error on the head reinstall.

I know that I struggled with the POS Harbor Freight torque wrench to set the second torque spec (45 ft.lbs. before you turn bolts 90 degrees) - I was difficult hear/feel the "click". Plus I reused the head bolts. It was the second time bolts were used as the head has never been off the block.

Frustrating, as the whole damn rabbit hole episode was due to a snapped head stud at cylinder 2 (I think) as the inner fender bulges inward right there, limiting access for drilling.

I took the head to a machine shop where the guy was able to remove the remnant of the stud and install a new one. He also cleaned the head in his parts cleaner and removed the residual head gasket from the surface (not sure how). He didn't machine the head.

The PO was very diligent with the car, and I have a pretty thorough maintenance and repair history. Has 140K, and nothing seemed weird when I had head off the block. Valves looked okay, a bit of carbon on the pistons, no ridges in the cylinders. Engine ran great.

Now I'm paranoid about the head. Why in earth would I get 210 on cylinder 1? I get the low compression on the two middle cylinders.

Does anyone know of a good machine/head repair shop in Charlotte, NC? I am going to have to bite the bullet and tear it down again, but I want someone who knows Volvos to assess the head and valvetrain for problems. And, I'll use new head bolts and buy a better torque wrench!

Thankfully with WFH I don't have to rely on this car to get around.
 
The 210 is not at all realistic. Cannot conceive of how that would be possible. The others could be cam timing problem. If the valves are open some when pistons are at top you are going to get strange readings like that.
 
Could be possible if there was some liquid hanging out in that cylinder, partially filling the chamber.
 
JohnMc said:
Could be possible if there was some liquid hanging out in that cylinder, partially filling the chamber.
Click to expand...

Or, just perfectly sealing the rings. I have seen compression numbers that high with a little oil in the cylinder to seal the ring. The compression usually drops to 180-185 pretty quickly.
 
Back when I worked for a Volvo shop/yard, it was not at all uncommon to see B230F engines showing 175-200 psi compression numbers after being run for a few minutes at varying rpm. B23F engines frequently would show 225-230 psi straight across.

I would've had the machine shop skim the head while it was off, though. Even though you reinstalled the same head onto the same block, there may've been some slight warpage, which may be causing the head gasket not to seal properly.
 
Since John mentioned warpage. I would suggest you measure the head for any warpage. Cam timing should be double checked. If not the cam timing then valves or rings are leaking.
 
I did a compression test on a B230E that had a recent head job. I ran the engine til it was hot, locked the throttle WO and my test results were all between 200-212.
 
petebee said:
Do as the man says...repeated test and all cylinders measured 210. Tester hose was not seated properly. Phew. Gauge is likely a bit optimistic.
Click to expand...

I don't envy that feeling you had when you first did it. Glad the retest yielded positive results and let's hope that you don't regret not machining the head !
 
mhgreen said:
I don't envy that feeling you had when you first did it. Glad the retest yielded positive results and let's hope that you don't regret not machining the head !
Click to expand...

Yeah it was a relief...did not look forward to doing the job twice. Due to the reason I took the head off (to repair a broken stud), it didn't seem to make sense to machine it since the cause was not overheating/blown HG. In any case, fingers crossed. Still need to check on the timing just for peace of mind.
 
what compression tester do you have? I recently bought a lisle from summit and got 180psi +- 1% on my 348k mile engine... which I too thought was a little bit optimistic.
 
The wide gap among those numbers is troubling.

I recently went through almost the exact same thing. Maybe there's something in my mess that can help you get through yours. You can scroll to the very end for a nutshell list of what I think you should do before sending your head out for machine work.

QUICK BACKSTORY
When I opened up this B20 I saw no detectable wear on the cylinders and found no metal on the drain plug magnet. The oil pressure was good, and the compression was up over 100psi on all four cylinders. There was only one thing that gave me pause ... a couple of the head bolts were really stuck. I had to use a 4ft breaker to get them loose. I bright-sided this and just told myself that they had been in there since 1973, so they really didn't want to leave. With all of this in mind, I decided on a regasket instead of a full rebuild.

PROBLEM
After the first start up, I spotted a couple tiny drops of water on the timing cover. I took off the valve cover to do a final torque and there was milky oil. I did the final retorque to 65lb-ft, a few of the bolts POPPED and turned about 90 degrees. Then I had a ways to go before the torque wrench clicked at 65.

MY FIRST THOUGHT
stupid harbor freight toque wrench!

MY SECOND THOUGHT
Maybe it's not the torque wrench? I definitely chased all head bolt threads, but I did not use a bottoming tap = shame on me. In other words, crud or imperfections in the threads could have given me a false reading during the first two torque cycles. The head might have only been torqued to 40lb-ft for all I know.

WHAT TO CHECK = do a leak down test! You can do this test using the hose from your compression tester or you can score a one-time use crappy LD tester from Amazon or rent one from Autozone.

MY RESULTS
compressor line pressure set to 100psi
leak down tester zeroed out with line at 30psi
engine cold - cannot start or warm up because of dead battery and I removed the rocker assembly
cyl 1 = 20% - radiator, intake, exhaust, and cyl 2 all quiet. Airflow up through pushrod holes = normal
cyl 2 = 35% - radiator, intake, exhaust, and cyl 1 all quiet. Cyl 3 = very slight whistle
cyl 3 = 25% - radiator, intake, exhaust, and cyl 4 all quiet. Cyl 2 = very slight whistle
cyl 4 = 20% - radiator, intake, exhaust, and cyl 3 all quiet. Airflow up through pushrod holes = normal

I removed the rockers to rotate the piston through its stroke to see if the numbers changed, which would indicate a scratch in the cylinder. I found that the % remained unchanged throughout the stroke, so no major scratches.

Notice #2 & #3. There's a problem there, so the head had to come off.

NEXT THING TO CHECK = flatness
you can order a machinist straight edge from Summit or Jegs for $50. You can get feeler gauges anywhere. Get a set that goes all the way down to .001.

MY RESULTS
I got a couple of spots on the deck that showed .0015 gap - same as before. These gaps lined up with the seepage marks above. Luckily, I could not get a .002 to fit, so I now know that the block and head are not compromised. This points toward improper torquing or (worst case) a crack.

NEXT THING TO CHECK = threads - a lot of people will disagree with this one! I was one of them until now.

fetch

I'm not proud of this job, but I did take my time and chase all threads with a standard tap when I did the re-gasket. Unfortunately, I didn't use a bottoming tap on the head bolt holes because I didn't have one on hand - shame on me! Here's a pic of the first hole I hit with the bottom tap. That's enough to throw off the torque, especially if each hole is crudded up at the bottom.


fetch

Here's a pic of a clean bowl I used to catch all the crud as I re-tapped each bolt hole. That's enough to totally throw off most torque specs, no matter what brand wrench.


NUTSHELL
Do a leak down test using a rented leak down tester.
Pull the head and check for flatness using a $50 machinist straight edge and feeler gauges.
Use a bottoming tap to clean the bolt holes all the way down.

I hope something in here helps. Best of luck!
 
Last edited:
John242Ti said:
Back when I worked for a Volvo shop/yard, it was not at all uncommon to see B230F engines showing 175-200 psi compression numbers after being run for a few minutes at varying rpm. B23F engines frequently would show 225-230 psi straight across.

I would've had the machine shop skim the head while it was off, though. Even though you reinstalled the same head onto the same block, there may've been some slight warpage, which may be causing the head gasket not to seal properly.
Click to expand...

There can be a caveat to machining a warped head. If you take out the warp by machining the contact surface you can create a new scenario where the cam sills are now not straight.

Did you have the head inspected by a machine shop ?
A decent shop will be able to tell you if it's warped/how much/specs.

I've heard of cases where someone just torques down a warped head(from the center typically), to avoid the mentioned situation, basically kick the can down the road for a bit.

If you discover the head is not sealing, find out what the acceptable range is for warped, and have the head inspected. If the head is out of spec, start looking for another head.



;-)
 
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