Thread: Head Gasket Issue?

Hi all.

I think I may have done a head gasket, but I’d like an opinion from someone with more experience.
I have a 96 Discovery with a 300TDI engine. Its done 320,000 km and I’ve had it for the last 120,000 of them.
The problem started a month or so ago, when I heard it gurgling when I pulled up. The temp gauge was halfway, where it usually is. Once it cooled down I found that the coolant tank was empty and it took 4L to fill. I removed the bung in the thermostat housing to make sure all the air was gone. I checked everything out and found that the bottom radiator hose had bulged at the hose clamp and had a small split. I believed this was where my coolant had gone.

I bought one of those Engine Watchdog temp monitors and fitted it, with the sensor under the bolt that holds a bracket to the block above the injector pump. It runs at around 81 degrees up-hill under load. The original gauge never moves from 50 to 80 degrees.
I ordered and fitted a full set of hoses as they were all getting a bit hard and old, yet still kept losing coolant. It was only a small amount, about 1L every 200km, but I couldn’t see any sign of leaks. Finally, this Saturday just gone, I found some green marks on the bottom radiator pipe. It had been leaking here and running along the channel. Being small amounts, as I haven’t done any long distances lately, I think it was evaporating instead of dripping, which I would have found sooner. I replaced the bottom hoseclamp with a nice wide one, topped up the coolant and drove around until I got it up to operating temp and spotted the new problem. Sitting at the lights I saw a big white cloud behind me. I got home and let it cool down. The coolant had dropped a bit over 1cm. It was still clean, green and had no sign of oil or anything in it. I checked the oil and it was also normal. I should mention, it doesn’t seem to use any oil. I haven’t had to top it up at all since the last oil change, 10,500 km ago.

The white cloud smells slightly of diesel, but not of oil. I started it this morning and all I got was the usual little puff of grey smoke I have always gotten when starting from cold. I drove to work, about 10 mins, and it was happily puffing out white clouds by the time I got there. I opened the expansion tank slowly to check the level and it was down slightly. It hissed a bit, but only for a few seconds. Later in the day I started it again, to show one of the guys at work what was happening, and the damn thing was fine. No white cloud. I couldn’t believe it. I went for a run around the block, and as soon as it got to about 55 degrees, it started again. I got back, kept it running and slowly opened the expansion tank cap. As soon as the pressure dropped, the smoke stopped.
Does this sound like a head gasket issue to you all?

I spent the day getting the head off and started cleaning it up to check out. One of the first things I spotted was these valve lash caps.
Two are totally worn through and the others are almost paper thin.

The two that were worn through were from cylinder 1. More on that later.
The inlet manifold came off easily. The exhaust manifold came off even easier, once I realised there was another nut behind the turbo body. I've had a slow oil leak
all down this side of the engine since I got it, and was told it was from oil vapour from the tappet cover being fed back into the turbo inlet and leaking out
through the manifold gasket. When I tried to remove the manifold nuts, the entire stud screwed out on almost all of them. None were tight.
Two of them I actually screwed out by just twisting the socket with my fingers. The gasket slid off when I pulled the exhaust manifold back and it was split into 3 pieces.
As you can see in the picture, it looks like the middle two exhaust ports were tight at some time.

The head bolts were next. 11 of them were so tight I had to use a length of pipe over the breaker bar to get them started. The other 7 I was able to loosen
with one hand on the bar. Not good. I also realised at this point that with all the bits I had ordered, I hadn't thought of new head bolts. Oh well, its overnight from Hobart.
The head came loose with a couple of knocks with the nylon hammer. That's when I found I hadn't drained the coolant down far enough.
After the flood, I lifted the head off and gave it a rough clean-up. The gasket came off easily, only sticking at one spot on the block. I mopped out most of the spilt
coolant and checked things over. The glow plugs came out easily. Two of the injectors did too. One I had to wriggle a lot, but it came loose. And one is stuck.
I tried turning it slightly, but its really tight. If I try to undo it, it happily screws apart, but I want it all out. After an hour of swearing at it, I took the top part out,
filled the hole with WD40, as that's all I had, and screwed it back together. I'll leave it overnight. If that doesn't loosen it, I will make up a slide-hammer and try to jar it a bit.
Anyway, here are some pics of the bits. I cant see any sign of a blown head gasket. Or any cracks. It all looks nice and clean. In the pics, all I did was spray some WB40 on a rag
and wipe over the block, head and old gasket.
If you look at the inlet valve of cylinder 1, you can see a weird chalky build-up in the valve face.
One of the guys we share shed space with offered to do an electro-static test on the head to find any cracks, but I have to get the injector out first.
Once I do that I can also sit it on a sheet of glass and check it for warpage.
Can anyone think of or see anything I've missed? I just can't see signs of a blown gasket or cracked head.