issics

Hi everyone. Just wanted to say hi from the UK. I have found this site to be an absolute goldmine of info and well done on being an awesome site.

I recently bought a 1996 XJ 4.0 PETROL non runner that had a suspected blown head gasket.

Water in oil with the usual cream effect so I stripped it down and took a look.
On closer inspection the head gasket looked a bit destroyed but mainly there was a problem with piston number 2. It had melted and damaged the piston sleeve in the process. I took the piston out and cleaned the shaft out where the damage was. Once it was all cleaned up the sleeve was actually ok, what looked like a damaged sleeve turned out to be melted aluminium from the piston still on the sleeve. This came off easily and a new piston was installed.

I then assembled everything back together and also installed a new thermostat and flushed the system and started it up. It took a few attempts to start but eventually fired. It was ticking over ok but sounded like there was a misfire to it. I left it standing on idle, it warmed up ok so took it for a test drive. The misfire was still there slightly but this may be due to old plugs etc being re-used. It stayed at a constant temp for around 20mins but I wasn't getting any heat from the heater and the heater pipes were still cold.

After about another 10mins the temp gauge was reading just over 100deg and the fan kicked in. I continued to drive like this but the fan wouldn't go off, even when the outside temp is 2deg here in the UK at the min so the air should of contributed quite a bit. Shortly after this point the needle just jumped and went through the roof. At this point I was back home so turned it off to cool down.

When it had cooled down I checked the coolant level and everything was ok with no leaks etc.a bit I tried to re start the truck but it wouldnt go, foot to the floor and still wouldnt go. Left it a bit longer and it eventually fired. Out of the exhaust there was quite a bit of white smoke but this gradually cleared as it warmed up. I left it standing at idle for about the same amount of time as before and it just overheated again.

I'm at the point where I could do with some insight please guys! In short Ive replaced the head gasket, checked for cracks etc in the head and its ok, ive got a slight misfire and no hot air at the heater.

Many thanks for reading this and thanks for any replies that you can give!

PLEASE HELP!

Radi

That engine got pretty hot to melt aluminum. Did you check the head and block with a straightedge and feeler gauge before reassembly to see if either warped?
Check the head for any cracks? Check the compression after reassembly?

You'll probably find more than one engine sensor damaged from the heat.
At bare minimum I'd change the coolant temp sensors and spark plugs and pull the water pump to check the impeller. There is a reason the head gasket blew in the first place that may not yet be corrected.
Some thermostats are known to have issues. What brand did you use?

issics

Thanks for the reply. I checked the head and block for warping and they looked fine with an edge on them. No compression test as yet as its sunday here and no garages open.
The truck actually came from an RAF pilot at RAF Lakenhurst which is a USAF base in the UK. In the truck were components from the US including a gasket set, stant thermostat and radiator cap like this

Radi

Glad you checked those things before reassembly, lol. Had to ask anyway.
The sparkplug from the bad cylinder, perhaps some aluminum blasted up in it? That might be the misfire. Check the water pump too, the impellers rot away and they stop moving water.

issics

Thats the next idea in the morning to check the pump. If its not that Im afraid it will have to go to the breakers or sold as a non runner as I cant spend anymore time on it. It was originally bought just for the bits on it, skyjacker lift kit, brand new 31" mud terrains etc but thought I would try and bring it back to life as a project.....but I don't think it wants resurrecting!

DFlintstone

I hope you installed the T-stat with the "business end" towards the engine, and the hole up at 12:00 if there is one. You can always test it in boiling water, (212* of course ).

Yea, like Radi said. I've seen posted photos of pump impellers that had corroded to flat disks. No fins. Do you see coolant moving with the cap off? Hoses getting hot?

A quick head gasket test. With the radiator topped off, and the cap off power/brake it. If the HG is really bad it might geyser. Or steady bubble is not good. Some surging is normal.

Fan clutch?

issics

Havent really looked for movement of coolant but will spend some time on it tomorrow. It was too late in the day to delve any further. No the heater hoses arent getting hot but the main rad hoses are red hot. Can you give me the head gasket test in dummies terms please as im not too sure what im supposed to do! geyser!?
Thanks for your reply also.

DFlintstone

Yea. It's not complicated. I call the coolant surrounding the cylinders the "water jacket". When the plug fires to drive the piston down the combustion pressure goes through the roof. The head gasket keeps those 2,500*(F), gasses from going into the water jacket. (that can heat the coolant fast).

So the idea is if you fillr' to the brim, hold the brake solid and give it moderate throttle in drive, if gas is getting past the HG into the coolant, it will bubble out the top of the radiator. ("gassing it" up's the combustion pressure). I've seen it so bad a column of water shot up and slammed into the hood! Or if it bubbles consistantly that's a pretty good sign combustion gasses are getting into the water jacket.

This will not tell you there are no cracks and the HG is good, but it CAN tell you if something is wrong.

issics

Ah I see now. Thanks for that, ill try it tomorrow and post back!

DFlintstone

I guess the basics make scene. Pump, T-stat, belt, Fan clutch, Radiator clogged? Don't crush it, (ship it to Radi!) Good luck!