Getting water into combustion chamber

I blew the head gasket on my 94 XJ6. I took the head in to have it tested and milled flat & true.
I saw no visible cracks in the block or head. I replaced the head gasket and head bolts. Torqued everything to specs and now when the engine warms to operating temperature, I get a cloud of steam coming out the tail pipe.
It does not produce the steam until the car warms up. I haven’t tried increasing the torque on the head bolts, as I didn’t want to create a bigger mess for myself.

I am at a loss as to what to do next. Perhaps one of you more talented individuals out there can help figure this out for me. I just can’t figure this out!

Thanks,

Wayne

Is it consuming coolant? Has the system been pressure tested?

Now that the new gasket has been through a few heat cycles, loosen the acorns and retorque them to the original spec, one after the other, in the same order as shown in the shop manual.

Yes, I lost coolant and I did have it pressure tested

Andrew,
Do you mean to torque the deadbolts again?

Thanks

Yes. If it was a composite gasket then it will have compressed a bit during the heat cycle. One by one:

Witness mark the nuts and head with a felt marker.
Loosen that nut 1/2-3/4 turn.
Retorque.
Check if the marks line up again.

If the marks all line up again or only a few degrees past where they were, then you’ve probably got a leak elsewhere.

If the marks are more than a few degrees past the mark, then you had lost the clamping pressure between the head and block because the gasket has been compressed during the heat cycle.

(Presuming that everything else was done right, it may just need retorquing after the heat cycles.)

Thanks, I will give that a try.
Would you suggest taking it out for a spin and getting it warmed up before re-torquing .

No, you want to get it up to normal operating temperature, which I thought you already had, then let it cool back down, then retorque.

1 Like

Also, a plug read would be in order: if coolant is getting into a combustion chamber(s), that will help identify which one(s).

1 Like

Yes, a clean plug will indicate where the leak is. If you’re loosing coolant (after the level has stabilized, of course) then I‘d worry. The pressure test indicated what?
Also, you should smell the coolant, but don’t sniff the exhaust for long, obviously. I’m guilty of such things. Did you consider that there could be lots of water in the exhaust pipes from when the gasket failed in the first place, now slowly boiling off? I‘d watch it and then consider the tips. But of course if you already know for sure that it’s not tight all the above is superfluous, and if Andrews tip fails you then it’s probably time to go back in and re-examine if everything lines up nicely.

And keep in mind the head bolts are “stretchable bolts” and supposedly can only be used, IIRC 2 times before they are recommended for replacement.

Andrew …

I always come back to “how did the factory do it ?”

I have no idea, but I’m guessing that when the car rolled off the assembly line they didn’t take the time to run it for awhile and then take it apart to retorque the head bolts … or did they ?

Did the cars originally have composite gaskets?

(tbh I didn’t even notice that the question was on XJ40)

Wayne could also try a leak down test, and see if pressure is arriving in the cooling system, but he already suspects that.

Well, last night I re-torqued the head bolts.

I took it for a short ride and didn’t notice the huge steam I had previously been generating!

This morning, however, the steam was back. It wasn’t nearly as bad though.

I will try another leak down test and compression test tomorrow when I am less depressed.

Thanks for the help and I will keep you posted.

Wayne

Wayne,

That is typical of a leaking head gasket. When the engine is running, there is minimum intrusion of coolant in to the cylinders from a minor leakage channel in a head gasket due to the compression pressures in the cylinder being greater than the pressure in the coolant system.

When the engine stops, there is zero pressure in the cylinders but since the water pump is no longer circulating coolant throughout the engine/radiator there is a temperature generated gradual increase in coolant system pressure due to the residual heat in the engine. That increase in pressure forces coolant through the tiniest fault in the head gasket in to one or more of the cylinders so that at the next start-up you get a lot of steam out of the exhaust. In the worst case, if a lot of coolant gets in to one cylinder there is a possibility of ‘hydraulic lock’ the next time you crank the engine resulting in a bent con-rod! (BTDT!)

However, it does not produce the steam after some warm-up, does that change things?

I’d avoid any more running of the engine: steam erosion is a serious matter.

Pull the head, and determine if it’s the gasket, and use new studs.

Not to mention hydro lock on starting, or combustion pressures spitting out core plugs (or splitting a rad seam).

1 Like

Wayne,

One other thought (from bitter experience!). When you fitted the head bolts after changing the head gasket, did you ensure that the blind bolt holes in the block were clean, dry and in particular free from oil which may have dropped down there when you removed the head and/or cleaned up the surface before fitting the gasket? If an amount of oil remains in those blind head bolt screw holes you can get a false torque reading due to the bolt ‘hydraulic-ing’ and the head gasket seal is imperfect.

Bryan,

Glad to see you are still on the forum.

I have had the head off twice and new head gasket both times. This is the closest I have come to minimizing the leak, but there is still quite a bit coming out.

In response to David, no, the steam does not go away. It is just not as prevalent as it was when it first blew and when I put in the new head gasket.

The head has been milled and new gasket again installed. I have now re-torqued the bolts, so any further adjustments, whatever they may be, will require new bolts as well.

Tonight, or tomorrow, I plan on doing another leak down test and compression test.

This is my 3rd XJ40 and I sure have acquired some nice tools along the way!!!

Thanks Bryan and all the rest of you out there.

Wayne