I replaced the head gasket in my 2005 S40 2.4i. The head gasket had been blown due to overheating. There was signs of coolant passing head gasket and dumping into the block between 1&2 and maybe 2&3. I resurfaced the surface of the head and then using a good straight-edge and feeler gauges, determined it was flat. I checked the engine block using the same straight-edge and feeler gauges and was convinced the block was not warped at all. I checked the cylinder bores for any unusually wear, marks, scoring, etc and was convinced all was good here. I carefully reassembled the top end set cam timing using the cam alignment tool. Put everything back together. Double and triple checked my every move when torquing bolts, using new TTY bolts. Of course replaced all coolant and oil. I drained the fuel tank as it had been sitting a long time, replacing with fresh clean fuel.

Attempts to start have been without success. I’ve determined I’m getting spark but it’s not firing. I have good fuel pressure but not sure if maybe the injectors or varnished and clogged from sitting. By the way, I did mix some injector cleaner in my new fuel just in case.

Now for the big disappointment… my compression check… #5… great pressure. The rest… not so great. No really in the realm of good. I haven’t done a wet test yet, putting a little oil in the cylinder for the test. I will do that when done posting this and leaving it to soak and maybe get some input.

Could my visual inspection of the cylinder bores have been bad to accept? Could the the rings be trashed without any damage or scoring to the bores?

I might also add, my generic compression tester is difficult to use as I don’t think it is specific enough with the deep spark plug wells. I however don’t thing I would have gotten #5 to read 130-135 psi and only
35-40 on the others… but 🤷🏻‍♂️!

Anyway, any suggestions? Roll it to the curb?! lol

Thanks in advance.

Randy

 

Sure, Did you try a wet compression test - squirt a little oil in each cylinder, spin the engine a few times to get the oil around the rings and test compression again? If still low do a leak down test to determine where the compression is leaking. You will be able to hear air leaking into the intake or exhaust if the valves are not seating, or pressure will come out of the oil cap if the rings are not seating. Then either pull the head back off and have a valve job done, or decide if you what to deal with piston rings. My bet is the valves are not sealing. Whenever I have done a head gasket for overheating, the head is sent to the machine shop for straightening, a valve job and valve adjustment.

A leak down test uses compressed air into each cylinder one a a time at tdc or at least with both valves closed. You can then measure the percent of air leaking out either through the valves or piston rings.

 

Thanks for the reply and ideas. I had put the tools away yesterday so will do the wet test today. This is probably a dumb question but I’ll ask anyway. Is there a fitting readily available that can be used to hook an air compressor hose into a spark plug hole? 🤔😬 I have to assume that is the only way to do this.

 

Yup… answered my own question… adaptor for compression tester with male air chuck fitting… is it that simple? 😬🙄

Off we go to the garage.

Thanks!

 

A leak down test is usually done with a gauge as shown. Sure you could put compressed air in and listen/feel for a leak, but a real tester is more accurate. Perhaps your local auto parts store has a loaner program for that tool?

 

Wet test showed a little better compression numbers and though I didn’t have the official leak-down test tool, I came to the concluding that at least intake valves on 1 & 2 are leaking. My local parts store doesn’t have that tool. I have the head pulled back off and I think I have a valve spring compressor and valve lapping tool on its way later tonight. I reinspected the cylinder bores and still see no scoring so would guess between that and the fact that there was still oil pooled up on top of the pistons when I tore it apart, that the rings are still intact. I should’ve known to go through the valves when I had it off before but didn’t. On a positive note I’m confident that the rest of my first head gasket replacement had gone well. Live and learn. Time to order another round of head gasket replacement parts. 😬 At least the water pump is done and I have the timing belt already.

Any other suggestions before I throw it back together?

 

I might add that the second round of compression tests were with a compression tester with a nice long adaptor to get good and tight down in the spark plug socket. I am not completely confident on my original round of tests. IDK

 

You have solid tappets - you will need to adjust 20 valves after you make sure they seat. (and your valve guides are still in good condition.)You will need something to hold the cams down to be able to measure the clearance. On this thread https://volvoforums.com/forum/volvo-...-start-107868/

someone posted a picture of a partial homemade tool. Take springs off, install cams, tappets and valves, measure clearance, calculate needed tappet and purchase or you can remove some of the tip of the valve. There's an attachment on the valve grinding machine I used to use that grinds the tip of the valve stem exactly flat.