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Cyl 1: 20%
Cyl 2: 8%
Cyl 3: 30%
Cyl 4: 8%Leakage was through exhaust valves on all counts. Could not observe any leak past intake valves, rings, or head gasket.
Yes, when my crank and left cams are aligned, my right cams are 5 teeth retarded.
I realigned and reinstalled the timing belt and performed the leak down test again. Cyl #3 is at 30%. Bent valve or normal wear and tear? (Remember 383,000 miles.)
Should I shell out the ~$100 for a timing kit on Rockauto.com?
Okay, okay, I lied. I didn’t reinstall the belt. I just took it off and made sure all the cams have free play so I know the valve are closed. And crank sprocket is aligned so pistons should be halfway. Isn’t this sufficient for an accurate leak-down test?
By the way, it was my idler sprocket bearing that got munched.
Well the leak down test won’t change after I reset the timing. I found top dead center of the compression stroke using a water balloon on the end of the leak down tester hose. But if I reset timing and it runs normal, I’ll know the 40% is okay, and it was like that before.
Until now I hadn’t looked at how expensive the timing component kit is (over $320 at O’Reilley). So as much as I don’t want to have to do the belt job twice, I sure don’t want to do it for $320 for no reason.
So that’s good advice. I’ll probably reset timing and see if it runs normal.
A quick update while I’m at it: after having the valves reground several weeks ago, everything continues to run great.
Although I didn’t block off the coolant passages while sanding the the block, everything is fine. (Note that the shape of and design of my coolant passages made it very difficult to properly block off, and that my water pump is easily accessible if I need to change it.) Also, the oil passages were only blocked for 75% of the sanding, and I changed the oil before running the car once the repair was done. So hopefully any grit is handled by the oil filter. Surely enough time has not passed for any wear to show up.
Can’t remember if I mentioned it earlier, but what I thought was maybe a squealing water pump pulley shaft that developed a day after the repair, turned out to be only a screeching belt as verified with some belt conditioner. A liberal application of belt conditioner took care of 95% of the noise. Flipping the belt around took care of the rest. I will now always mark the direction of belt rotation before taking off and putting back on old belts.
So at first I had all the spark plugs out and I didn’t prop the throttle valve open. I set #1 to TDC of compression stroke. When I introduced pressurized air, it escaped out the leaking intake valve into the intake manifold. But since I didn’t prop the throttle valve open, the pressurized air flowed into the intake manifold and then into whichever cylinders had intake valves open since they were on their intake strokes (as well as a little bit into whichever cylinders also just had leaky intake valves. And since I had all the spark plugs out, that compressed air flowed straight out the spark plug holes. You can see how without verifying propoer test conditions, someone could easily say. “Oh, well you obviously have a head gasket leak since air is leaking from one cylinder to another.” But in my case air was “leaking” from one cylinder to non-adjacent cylinders.
I then reinstalled the spark plugs, but I still neglected to prop open the throttle plate. Now the compressed air from cylinder 1 flowed past the leaky intake valve, into the intake manifold, back into other cylinders and out any of the open exhaust valves. (Remember that 3 cylinders had substantially leaky intake valves, and all cylinders has slightly leaky exhaust valves.) Again, you can see how without verifying proper test conditions, one could easily say, “Oh you’ve got leaky exhaust valves since the air of coming out the tail pipe.”
When I next propped my throttle place open, air flowed freely out my throttle body and I finally figured out what had been going on. (Note that while most of the air follows the path of least resistance, it still goes everywhere. With throttle plate propped open, and spark plugs removed, some air still came out the spark plug holes to varying degrees of pressure depending on how far open their intake valves were.)
The moral of the story is that it is important to leave spark plugs in and prop your throttle valve open when doing a leak-down test. I often see instructions (including yours) that leave out one or both of these important steps. The other lesson is that leaks on all or most of you intake and exhaust valves make diagnosis a little trickier. I suspect that a single burnt (aka cracked or broken) valve is much easier to diagnose. Although I guess my symptoms wouldn’t be so different from bent valves.
Final update and summary:
Contrary to the title of the post, I had low compression on cylinders 1-3, not all four. (Faulty compression tester to blame, or maybe, just maybe, dying battery from all the cranking, but I don’t think so.)
Leak-down test was essential to determine that intake valves were the primary source of the leak. Note, however, that the exhaust valves were leaking a bit also which can confound the leak-down test a bit. Be sure to open throttle valve for test, lest air flow past a leaking intake valve, into the intake manifold and back into another cylinder (which happens to have it’s intake valves open) then out a spark plug hole (if plugs are removed). This would make it look like a blown head gasket.
Pulled the head and determined that at least some vales just plain weren’t seating tight. Shining a flashlight fro behind (in a dark room) showed the leak on some. Rigging up a vacuum tool showed the leak on all. This was confirmed by a vacuum test at the machine shop.
Machine shop confirmed that valves were not bent, agreeing with my own test using a drill press and a dial gauge.
No build up was found on any of the valves or seats.
I had the vales and seats machined, as well as the head decked to save me the time of cleaning the head mating surface myself. Machinist also said that valve guides were a bit sloppy (although I don’t think I was consuming any oil). Had new guides pressed in, and new seals installed since they came in the head gasket set anyway.
Car went back together and runs again. Just a very tiny bit rough, but strong as ever. At 220k, it’s entirely likely that any tiny roughness is the result of injectors, fuel filter, plugs that haven’t been changed yet, who knows what else.
Lesson’s learned: If you use any abrasive sanding method to clean the aluminum block mating surface, and it’s too difficult/impractical to plug the coolant passages, flush the cooling system after or expect your water pump to fail after a couple days. Mine is not leaking yet but it’s squealing.
Nevermind, I got it.
I jacked the car as high as I could so that my breaker bar wouldn’t bump into the ground. I used a 2 foot harbor freight breaker bar and a homemade pulley holder (pictured below). And most importantly, I employed a very large, strong helper. Expect your helper to grunt and groan even with that two foot breaker bar.
We successfully got the match mark on the bolt moved approximately 90 degrees past the match mark on the pulley. This is close enough I figure. No need to be ultra precise.In case anyone is wondering, those are grade 8 bolts on the pulley holder, and even still the threads get tweaked when using it. Grade 5 nuts though since I figure they’ll come off the damaged threads easier. I did have to take the bolts out and flip them around pointing out the other side of the tool in order to use it in opposite direction for removing and reinstalling the bolt.
I should have pre-drilled the nail holes or somethings so that the 2×4 didn’t split, but as it was, the shear force was on the upper nails, not the lower ones where the wood split worse.
[IMG]http://i66.tinypic.com/2choxhs.jpg[/IMG]
So anyway, the valves aren’t bent. Got any idea why my valves lost their seat?
This article has good info that helped me understand how my valve seats may have warped or receded. My guides were ever so slightly worn (although not enough to smoke) and several years ago one valve clearance on a single valve was about .001 out of spec. Could have got worse and maybe excessive valve train wear caused the seats to wear.
A lot of stuff in that article relates to burnt valves which I didn’t have, but perhaps “excessive valvetrain clearance can make the valve seat with heavy impact, causing valve face wear.”
You guys are automotive forum rockstars.
I took the head to the machine shop. The valves are NOT bent. They did not contact the pistons. No valve float, no mechanical timing issue. The shiny mark I saw with my shitty inspection camera must have just been glare/reflection/a mark in the carbon from the inspection camera itself.
There isn’t any carbon build-up on the valves or seats. The valves are not burnt, cracked, nothin’.
The sole proprietor of the machine shop for the past 30+ years said, “sometimes valves just lose their seat.” He reground them and now they seat perfectly. I was able to pull near perfect vacuum on all the intake ports. I’ll have the car back together this weekend and I fully expect it to start and run perfect.
I’m not looking for a supernatural explanation. Just an actual explanation. And all of those offered so far have been proven wrong. Nothing to be butt hurt about.
I want to understand what happened because I want to know if it will happen again or if it can be prevented. At least one intake valve on three out of four cylinders weren’t seating well enough to maintain enough collective compression to start the car. Cylinder 4 was fine.
The valves aren’t bent. I spun them (by hand) in a drill press and checked them with a dial gauge.
To be clear again, the cam timing was not off and there is no indication that the valves made contact with the pistons.
The valves aren’t seating fully. With the head AND cams removed, I can not pull vacuum at the intake port on cylinders 1 through 3. There does not appear to be any deposits on the seat or valve. The car did not overheat.
Synthetic blend oil had 30k miles on it and was 1 quart low. No other problems.
What happened? I am going to spend $100 on gasket set and bolts, and $260 at the machine shop to regrind the valves or whatever. Am I throwing my money away?
So I learned how to do a proper leak-down test…
Cylinders 1 through 3 are all leaking out the intake valves. (Nothing is leaking out the exhaust as stated earlier.)
I pulled the head, and I can see light from a flashlight coming through one of the intake valves on cylinder number 1. No light on the others.
Timing was dead on. No sign of bent valves, and no reason for it either.
How should I proceed? Why would intake valves go from seating perfectly 4 years ago, to only holding 40-80 psi on only three cylinders? Why was the car running basically fine just before it died?
So the leak-down test shows major leaking on cylinders 1 through 3. (Turns out cylinder 4 is good. A new compression gauge and leak-down test show it’s good.)
Cyl 1 is leaking out the throttle body. Cyl 2 and 3 are leaking primarily out the tailpipe. So I’m thinking the valves are bent slightly.
Inspection camera does not reveal broken/burnt valves. When I plop my long screwdriver into the cylinder while finding TDC it leaves shiny marks in the carbon on the center of the piston. Well, on at least piston #1 I can see a single crescent shaped shiny mark off to the side of the piston below one of the intake valves. (I don’t see any shiny marks on the other two beside those from my screwdriver which are less pronounces on those pistons.) So I’m thinking this was from the valve making contact. But they really appear to be seating so i don’t know.
Remember though that the valves are not contacting the piston right now. When I had the valve cover off, everything appeared to be in time. So what happened? All I can think is:
1) Could a chain have enough slack (from say a weak/failed tensioner) to cause valve interference without actually skipping teeth?
2) could it be something with the springs? But I can’t imagine how multiple springs would have suddenly broke or weakened.I’m stumped.
So the timing chain is good.
I set piston #1 at TDC on the compression stroke. I was able to insert a straight edge in the notches in the ends of the cam shafts indicating indicating that the timing chain hasn’t skipped a tooth or anything. Then I hand turned the crankshaft in reverse to check for excess slack in the chain. The cams gears began to rotate immediately suggesting no slack. Anyhow, slack alone shouldn’t cause a no start.
[quote=”relative4″ post=185689] you’re probably looking at ringlands. 220K miles is a good life for a Ford engine.[/quote]
Remember that the car ran perfectly before it suddenly wouldn’t start. I doubt that ringlands are the problem.
[quote=”ToyotaKarl” post=185740]Sounds like the timing is off or a blown head gasket.[/quote]
It’s virtually impossible that a blown head gasket would cause low compression in all cylinders. I also have no other symptoms of blown head gasket.
I’m at a loss.
Well thank you for all the info so far folks.
First I intend to do a leak down test. While doing that, I might also add to my chances of finding the leak by doing the following:
- stop the crank from spinning by propping a breaker bar from the crank pulley bolt to the ground
- attach a rented cooling system pressure gauge
- apply 150 psi to each cylinder at TDC to see if I can raise the pressure in the cooling system I would just look for bubble, but the pressure container setup on this car makes that tricky)
I am skeptical that either test will narrow down the leak, given that (a) it is likely very small, and (b) it could be lower in the sleeve (less likely), or in the exhaust port (possible).
After the test, I will simply tear it all apart and have a look. Joy.
[quote=”Rob781″ post=172446]looks like your to rich on all the plugs to me….. did you notice any liquid on any of the plugs? like they where wet[/quote]
Scan tool shows the long-term fuel trims are within plus or minus 5% which I belive is fine. Fuel economy is unchanged and same as it’s supposed to be. There was no liquid on the plugs.
[quote=”451Mopar” post=172454]I have heard those engines had a lot of problems?
Do a search on it, you might be better off selling or trading in the car and get a different car?[/quote]I’m pretty sure the most common problem is sludged up oil passages. I change the oil regularly.
If I sell it now, as is, I can’t (in good conscience) get more than a few hundred bucks for it. If I fix it, it’s worth a lot more, and then I can think about selling it.