I have a 1991 XJ6 with the 4.0. There is water in the oil the car has 95, 000 miles and does not run hot at all as a matter of fact after I purchased it I changed the oil and plugs and took it down to get it smog test and it passed easily.. When I began tearing into the engine thinking the problem is a leaking head gasket as was told by the seller, I notice water in the intake coupling between the throttle body and the mas air flow meter. Could this water have come from the "Part throttle Orifice Control Housing"? This part is located right above the throttle body on the plenum of the intake manifold. His housing has small coolant lines attaching to it. One of the lines the outboard one appears to be open to the intake plenum with a small orifice. Is that a direct connection between the cooling system and the intake of the engine? Is it possible for the engine to pull enough water and collant into the intake plenum to show up in the oil? Am I full of crap and don’t know what I am looking at being my experience is mostly with American cars? Is there any other way water could be getting into the oil (water pump to timing cover seal) or any other means. Does anyone have any thoughts? It would seem to me if the water was getting into the motor via a leaking head gasket there would not be any water in the intake area especially outside of the throttle body and being that the engine leans to the exhaust side. I would think the leak would have to be really large and would have a tendency to hydro lock the motor first to show up in the intake outside of the throttle body. Hopefully one of you has a suggestion that might save me from having to remove the head. I don’t mind going through the extra work to do that but if I can avoid it that would be great. I am contemplating blocking off all of the water ports on the block and head and pressurizing the block and head to the recommended operating pressure to see what happens. Now that all of the hoses are removed I can rule out the leakage of any pressure through a hose. Am I wasting my time here. Are there any other common problems to Jags where water would show up in the oil and not be a head gasket? Did I mention the car does not run hot at all?
Thanks

 

Welcome, I don't think Jaguars are supposed to be run hot ,normally temp gauge should sit steady .( 12:00 o'clock position ) .
I'm sure our tech experts to shed some light on your issues as well

 

There's an awful lot of stuff thrown in here, so let's break it down a little.

When you remove the intake elbow and convolute hose to the throttle body on an AJ6 engine, you will find mud. The crancase breather setup on this engine huffs oil and water vapor into the intake tract. Droplets of water are common, so is the white goo from the mixed oil and water: you might be seeing this inside your oil filler cap and filler neck, too. Fuggedaboutit. Normal byproducts of combustion, sometimes made worse by a little extra water in the fuel and overdue oil change interval, but not a sign of a fault. Is that what you are talking about?

When engine coolant enters the crankcase, the results are usually:

Increased level on the dipstick
Oil is peanut butter colored when the blender has been running for a while.
Empty the sump, and a nice stream of coolant comes out after the oil has drained.
Is that what you are talking about?

I know what you mean about alternate leak paths, the V12 will dump coolant into the sump when the timing cover gasket fails in just the right way. Been there.

Head gasket/ cylinder head/ cylinder block cooling jackets are the only possible point of failure that I can think of on an AJ6 engine that permits coolant entry into the crankcase. This does not necessarily cause an accompanying coolant temperature issue, but it may have been caused by a previous one...severe leak, bad thermostat, bad fan clutch etc.

I'd be doing the normal tests for blown head gaskets if I was sure that coolant was mixing with the oil. Pressure test cooling system, then crank the engine with the system still pressurized and all plugs removed. Drain the oil, then put the pressure tester on overnight and see if any coolant appears in the sump.

There is a 1990 bulletin about cylinder head corrosion at the cooling jackets: I have not seen this condition to be severe enough to scrap a head, but it happens. Usually a .010" skim and a new gasket is just fine. Head gasket faults on these engines are common, but more often lead to oil seepage past the pressure port and running down above the distributor: and failures of the combustion sealing rings bonded into the gasket that circle each bore. That's not what you have, and coolant in the oil is not a common result of a head gasket failure on these engines. It can happen, and if in fact you have coolant in the oil, I don't think there's another way for it to be getting there.

One footnote, if you do have the head off: there is a coolant hose on the intake side of the engine, coming from the water distribution pipe bolted to the block and going to the backside of the water pump housing. Change this hose while the head is off, it will only take a few minutes. This hose is called "the *******" hose for a reason, as you will find when the day comes that you have to replace it on a fully assembled engine. If you see a new one installed, you found out how the engine overheated and helped kill the head gasket. Those hoses burst, and dump two gallons in less than two miles or two minutes. Been there.

 

Having dealt with brits and headgaskets before I would agree with everything that JagTech has written. On the Land Rover motors when the head gasket goes generally you will find a steam cleaned spark plug or plugs.

x2 on replacing that hose while you have the head off it went on me about two weeks ago. It wasn't horrible but it wasn't exactly fun either. It took me longer to source a hose than it did to change. about 35 min to change 3 hours to find and get the hose.

 

You're lucky (and pretty good), the '89 doesn't have an air pump fitted so you missed out on half the fun. The rest of us just cuss and work a little longer at it.

 

welcome to the forum howlin....
Please note this is the new member section and all queries / tech questions etc should be posted into the relevant section / general tech help section.

Great work JTO

 

Hello,
Thanks for the very informative reply. here is an item by item response to your earlier reply.
Convolute hose and throttle body
It did look like mud inside, actually it looked more like grease, with white goo and coolant ("green"). there was no increase in the oil level when i first check the oil when i purchased the vehicle. But after changing the oil, plus, repairing 2 manifold vacuum leaks and returning form my emissions test (it passed easily) It did appear that the fluid level was a bit higher than when i first changed the oil.
Color of the oil
The color of the oil was peanut butter colored when i picked up the car and had it towef home as i did not want to drive it.After changing the oil and running it a bit and returning from the emission test I noticed it was kind of peanut butter colored again. I thought this may be due in part to the watery residue and white goo still working its way out of the crankcase. when I originally drained tyhe oil there was no stream of coolant that came out of the pan either before or after but the oil was peanut butter colored. This leads me to believe the leak in (hopefully gasket not cylinder liner) is slight.Are cylinder block cooling jacket problems very common? If so what percent of the engines do you see have a coolant jacket problem versus a leaking cylinder head? How would I find out and test for a leaking cylinder block cooling jacket liner leak. I am comtemplating making a plate that coveres the block after i have the head removed and repressureizing the block and look for leak down.is there a quicker and easier method to test for this? what is the normal operating pressure of the block and head?
Cylinder head
I had planned on have the head milled anyway .010 - .015 whatever it takes to get it smooth and flat. I will take your advice and look for oil seepage above the distributer. i don't think the car has ever been hot, i am not sure I can certainly speak with the person i bought it from and that might help in my history and diagnosis. Although all of the hoses under the dood appear to be original and some ever tore as I attempted to remove them. so that supports my assumtion on them most likely being original.

I saw this hose (perfect name for it) and the first thing that came to mind is i am gonna change this one for sure! As a matter of fact I will be changing all of the coolant hoses, vacuum hoses, water gasketst-stat, water pump, belts and fan clutch. I will probably even end up changing the radiator as well as I do not want to repeat any of this work a second time.
Part Throttle Orifice Control Housing
What is the story on this device? What does it do and why is it there and could this be a source of water in the oil( iam kind of thinking no)! Thank you again for all of your help and i hope my reply has shed more light on my situation and perhaps you have some more thoughts. At this point though I am thinking the head is going to have to come off.