First off, I've used this forum for a long time for fixing the numerous little issues with my first Discovery, and it has been a truly indispensable resource, so a big thank you to everyone for all the help. I love my '02 Discovery and have fun tinkering and off-roading with it. I did the head gaskets and a top end rebuild on it last year.

As the story starts, I had been looking for a project recently and found a 2003 with a really nice body and interior for really cheap. It had full maintenance records and everything was up to date. The previous owner said she was going down the highway when it just lost power and started steaming. She turned it off and had it towed home. When I got to it, it would not turn over and hadn't run for about a year, so I figured I maybe in for head gaskets and a little more.

I brought it home, hooked up a battery to find that it appeared to be completely seized up. I drained the oil and it looked old, but okay. I pulled the plugs and managed to break the crankshaft free with a breaker bar. Plugs and everything looked okay, good spark and good fuel pressure, so I tried to start it. It coughed and had a couple cylinders fire and eventually started up, but only held about 500 rpm at best and ran for about a minute before stalling. Water started streaming out from behind the front cover. So I dropped the oil pan and the front cover and replaced the gaskets, oil pump, and timing chain and gears. Everything looked good.

Still wouldn't run for more than a minute, coughing and rough. So I did a compression test and cylinder 5 had a compression of 0, and the best was 95, although these were done when cold. I added oil - no difference. The valve covers were leaking oil bad, so I figured I would take the heads off a take a look. Head bolts came out quite easy, especially on the back. Cylinders 7 and 8 definitely have coolant leaking through the head gasket. I can't seem to figure out why cylinder 5 has 0 compression -- the gasket, valves, and head seem visibly alright (I attached pictures). It does look a bit cleaner than cylinders 1-4.

I'm wondering if I should just put a new gasket on (after machining the heads) and see if that fixes the issue -- or is it a cracked block? It's a nice truck, and I'd like to keep it if I can.

TL/DR: Bought non-runner, no compression cylinder 5. Head gasket shows no signs of blow out on 5. 5 is a little cleaner than other cylinders. Any ideas?

 

That sounds like a possible cracked block to me. In my experience and also what I've heard from others. Head gaskets usually leak externally. Cracked blocks will often cause the fast overheat and steaming. Maybe not in all cases, but that's what seems to be the case in most. Also, the cylinders look rusted. Which can happen when you have coolant filling the cylinders.
Have you looked at the valves to see if they are hanging open on cylinder five? The rings could also be stuck in the piston grooves from sitting. Although, that wouldn't cause the zero compression reading.

 

Thanks for the response disc oh no!

That is interesting about the fast overheat versus the slow overheat. I think some of the rust-colored residue is old dried Dexcool - yuck! The valves are not hanging open on 5, but I suppose there could be other problems with the head (cracked?). I'll have a machine shop take a look. There are some very slight score marks on the sleeve, I'm not sure if that is an issue.

Maybe I should look into getting another engine for this rig? With Brexit, pound-to-dollar rate is low. Turner engineering short block?

 

If you've got zero compression, I would think it would be something obvious.
Also, did you mean you had 95 psi on all other cylinders? Because that's pretty low compression. Are you sure the timing is correct?

 

I agree, I feel like I am missing something. Here were the results from the compression test, averaged of 3 times cranking 5 times:

1: 59
2: 92
3: 30
4: 91
5: 0
6: 80
7: 31
8: 35

The engine was cold, I know that gives odd readings, but I couldn't get it to run long enough to heat up. Numbers are all over the place. When I did the timing chain, I found that the old one was a little loose, but didn't seem terrible. I followed the procedure in the RAVE, but I could have messed it up.

 

I would recheck the timing. Make sure that both valves are closed and the cylinder is at the top when the marks are lined up. Timing is not too difficult, but can be a little tricky when you don't have much experience with it. I remember the first time I did a timing belt on a Subaru. The engine is super simple, but one of the cams always looks like it's off. After you do it once, you know what to expect.
You may just be a tooth off or something.

 

I have never done timing before this engine. I'm not a mechanic, but I'm technically oriented. I had a Yamaha boat engine that was off a tooth and had all kinds of crazy issues. I'll check it again, hopefully it'll reveal something.

 

I would say, just take your time. Turn the engine over by hand with the timing cover off. Remember, you have to turn the crank 720* to make one full 360* cycle of the cam. Then recheck the timing marks and make sure you can line up the marks when they come back around.


Remember to make sure both valves are closed on the #1 cylinder and the piston is right at top dead center. When you have those two things set, the timing marks should be lined up. Keep in mind that both valves will not be closed again until after you turn the crank two full turns. (cam will turn once)


Hopefully that's all it is and you don't have any other problems with the engine.

 

Head coolant leaks may have resulted from loose torque since you said no obvious breaks in gasket and rear fire ring so rusted. Record of prior replacement?

Quote:

Originally Posted by disc oh no

I would recheck the timing. Make sure that both valves are closed and the cylinder is at the top when the marks are lined up.

Believe that if timing off enough for zero on #5 other cyls would be closer to that as well if timing was the main comp issue. Bad timing should be affecting more than one cyl.

Comp on #5 a mystery but since so clean and some rust must have been firing and burning off some coolant for some time prior to your purchase.

What does the other bank look like?

$.02
......

 

Maybe the intake cam lobe for Cylinder 5 is wiped?
If you can't get air in you can't compress it.

And looking at that head gasket it looks like #7 could be pumping hot gases into the water jacket?