Head gasket, Cracked Head, Blow-By??? Need some help diagnosing!!


New member
Aug 28, 2020
Texas, USA
Ok so here we go, I purchased a 2000 Land Rover Disco 2 last year for 500$ on an online auction and have spent COVID rebuilding her by hand. I have done an INSANE amount of restoring and once I FINALLY had every switch fixed, interior restored, new suspension, brakes, lift, ball joints, steering rebuild, and so much more.....I thought she was ready for the trail. I got her at 181K miles and the head gasket had been rebuilt already(at 102K) as it had a service manual in the truck actually. So I thought I had a little blow by but the engine has been running smooth and strong after new MFS, TPS, plugs, wires, new throttle body, inlet, heater plate, etc. gaskets all replaced.
Now.....bam all the sudden the truck is running super loud, but no over heating and no coolant loss.....I’m thinking exhaust manifold leak/crack.....NOPE! I’m literally getting high pressure blow-by(not sure this is right as it’s not within it cyljnder chamber) but exhaust fumes, vaporized gas and even spark are being pushed out between the block and heads on the driver side right between cylinder 3&5. Obviously I am getting misfires there too. I have attached to videos. I am guessing this is my head gasket, but has anyone ever seen this type of failure.
I’m a decent driveway mechanic but I’m a bit lost here. I don’t see an external crack anywhere and it seems to be being expelled through the seem betwee. Block and heads.
You can actually see spark expelled upon initial start of engine.
Engine actually runs fine, have no problem with power and runs down the highway on 35s at 75mph no problem beyond being loud as hell.....


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Well-known member
Mar 15, 2017
I had this problem on a '95 RRC with a 4.2L. Don't run it, it will have a thermal erosion cut made in either the head or the block (maybe both). My head had to be replaced because of this thermal erosion that showed up as a deep cut (ditch) in the head. Head gaskets do sometimes blow to the outside of the block. Makes it sound like a Fokker tri-plane... You're not seeing sparks that's combustion fire.


Well-known member
Jul 3, 2009
Portland, OR
Simple HG job. Its likely it got hot at some point. Whoever did the previous headjob may have just slapped a new gasket on without machining the head.