QuestionQUESTION: I have a 1963 xke with the 3.8 engine. I rebuilt the motor doing a rebore and new pistons. I've put about 3000 miles on the engine and still are using quite a bit of oil...about a qt every 250 miles. Got back from a 200 mile trip yesterday and checked the oil, found it a little lower than normal and decided to pull the plugs. One was fouled quite a bit.Can the oil be coming from the valve guides? The guy I bought the car from supposedly had the head redone, but it doesn't seem reasonable that I screwed up anything on the block so I'm suspicious about the head. If the tappets are "loose" or pitted can that cause a problem? I generally get a blue cloud when driving off from a light which I'm told is a valve seal problem.
ANSWER: Hi Jeff,
Usually valve stem seal problems are noted by lots of blue smoke on first start up but less as you drive. The Tappets have little to no effect on oil burning.
Blue smoke on acceleration is mainly rings. There is a test for a ring problem. Remove all the plugs and disconnect one side of the ignition coil. Run a compression test with the throttle open and be sure to spin at least 5 or 6 revolutions on each cylinder. Write down the results of each cylinder.
Then one at a time squirt about 4 shots of engine oil in the plug hole and run the compression test again and repeat on each cylinder writing down the results.
The second "Wet" test will be higher than the first but it must not be more than 10% to 15% higher. If so you have a ring problem.
Questions,
1. Did you check ring end gap and if so, what was it?
2. Did you install the scraper rings with the dot or number "UP"?
3. Did you stagger the end gaps on all rings?
4. When the machine company bored the block, what skirt clearance did they give you?
5. Did they hone to a 45 degree pattern after the bore job?
6. What kind of "Break-in" procedure did you use?
7. When was the first oil/filter change?
A stopped up crankcase vent system is a common cause of oil burning and jaguars are noted for that. Did you check it?
let me know,
Howard
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QUESTION: Ok, I'll try the compression test. The pistons were AE pistons. The data that came with the pistons was a little suspicious. It said go with a .0002 skirt clearance. The machine shop didn't believe the number, I checked around on the internet and found some info saying not to go with those numbers, guys ended up scuffing things. Ended up .0015-.002". End gap at that clearance came in right on, didn't have to file them, and installed the ringsin the proper groove, with marks up and with end gap staggeredIt was honed with a 45 degpattern. I ran the car pretty easy for the first 1000 miles. Did an oil change at 500. Breakin was with castrol HD 30, changed to castrol 20-50 last season, havn't changed it since, definitely due, been topping up with the HD 30 for awhile because I read that some of the other weight oils don't have certain additives that teh tappets like. I'll check the crankcase vent, I did replace with a XKSunlimited gauze filter, I can't imagine it getting all cruddy so soon though. The plugs read a little funny, 3 cylinders are perfect, 1 is oily, 2 get sooty in low speed driving, but after this weekends trip are looking right
ANSWER: It sounds like everything is as it should be. I would not expect that to burn oil unless that gauze filter clogged up during break-in. I have built a lot of XK and XJ engines since 1960 in jag dealerships and seen a lot of worn out valve guides but none that would use that much oil.
If it were mine, I would still run the dry and wet compression test if for no other reason than to get that out of the picture as I found that test to be good.
How is your case vent run? Could it be a problem?
The baffle plate was in the pan wasn't it? I did get one that the baffle plate was not in the pan and it was a problem with oil use.
Yes, that extra zero in a spec could cause big problems. I was teaching in a commercial mechanics school once and found a Motors manual with .0001" as skirt clearance.
Howard
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QUESTION: Finally got around to the compression check. Tested cold all cylinders were 145-155, hot 155-165. One cylinder that had oil was a little high, I attributed to the oil, rest were average. I went with 8:1 pistons when I rebuilt so the numbers may seem a bit low to you. At this point I'm assuming the oil I'm seeing must eb from the guides. Seem reasonable?
AnswerThe test for a ring problem is a "Dry" Compression test followed by a "Wet" Compression test not a cold and hot test. Run the dry test and add oil to the plug hole and run the test again and let me know what the readings were on each cylinder.
I started working on Jaguar in 1960 and rebuilt many in-line 6 cylinder jag engines from the XK-120 up to the 4.2 and never seen one use excess oil due to lifter clearance. Valve stem clearance can cause oil use but it is noted by a large puff of blue smoke on start up and then the smoke will not be noted much if any more. Since you seem to be concerned about the head work, you might use "Plasti-gauge" on the under side of each cam bearing to get a picture of the cam bearing oil clearance. Be careful not to let the cam rotate even slightly as that will smear the Plasti-gauge and make the test void.
Blue smoke on acceleration is rings. Either because of a ring problem or crankcase pressure due to ring blow-by or some other crankcase problem like a vent system that can not exhaust the normal pressure build up, or the lack of a baffle in the pan or the engine over full of oil.
Howard
