How to find TDC? / Valve Springs & Pushrod Replacement

I think I have a bent push rod or a collapsed spring and I'd like to try to fix it myself but I've never done it before. I have the manual and it does a fair job of describing the procedure but as usual the pictures are terrible and I didn't see the Top-Dead-Center mark on the crankshaft flywheel.

Can y'all tell me where I should be looking for it from the top of the bottom?

I bought a compression gauge to try to confirm the cylinder that's making the noise.

A little background...

I recently had been trying to get rid of the lean fuel mix codes, P0171/0174. I also had a missfire, P0301, I believe. That should be cylinder #1 correct? I replaced the spark plug wires and found that #1 was nearly cut in two. It's my thinking that this cylinder probably hasn't been firing for years, it's all fouled up and the valve may have been stuck open, allowing extra air into the cylinder causing the lean code. I think the valve busted loose when I started it with the new plugs and wires and (I hope) just bent a push rod or the wore the spring out.

I'm almost positive it's cylinder #1 but I'd like to be sure before I go taking the rocker arm off. From what I read in the manual, I MUST have the cylinder at TDC when reinstalling the springs.

Also, it mentions blowing compressed air into the cylinder to seat the valve all the way up, is that really necessary? I don't have a compressor, can't I just pull it up?

Any tips would be appreciated.

I would think what the book is saying is .... have each piston at the top of stroke as you replace the associated springs. Working on one cylinder at a time.. ... this keeps the valve from getting away from you and falling into the open cylinder.

I would think what the book is saying is .... have each piston at the top of stroke as you replace the associated springs. Working on one cylinder at a time.. ... this keeps the valve from getting away from you and falling into the open cylinder.

Ah, so I just need to find a way to keep the valve up?

Yes, .... plus ... as the piston is on top of its stroke in the compression/ignition cycle ... the valve springs (for that one particular cyl) are relaxed, or nearly so. So therefore, the springs are then easier to deal with ............... AND, both valves are seated.

Some folks like to poke a small diameter cord into the spark plug hole ... packing it in ... just before the piston is fully "up" ... then the crank is hand-rotated 'til the piston is "up" ... the cord is now smashed into the valve faces, holding them securely in-seat.

If I just want to replace a push-rod I shouldn't have to do anything special right?

I'd just take off the rocker arm, slide the old one out and the new one in, correct?

Hopefully it's just a bent pushrod... but that sounds too easy.

I recently did something like this ... on a V6 in a Bronco. Fairly straight forward. I would expect the Windstar to be similar.

I checked the pushrods and rocker arms on the suspect valve and they look fine, I haven't checked the rest of them yet but I'll get to it.

I'm going to take of the head off and check for a collapsed lifter which is my next suspect.

I got a quote from a local private mechanic to machine the heads and vacuum test the cylinders for under $300, is that a good price?

Could a leaky cylinder head be causing my persistant P0171/0174 codes?

I haven't done it on a Winnie, but I think the lifters are removable without touching the heads.... just the intake manifold. If you remove them, a cyl head repair shop can check for you.

I haven't done it on a Winnie, but I think the lifters are removable without touching the heads.... just the intake manifold. If you remove them, a cyl head repair shop can check for you.

:eek: I did not know that. You just saved me $300 and hours of work! I sure hope I'd have realized that after taking the lower manifold off though. I really didn't want to take the heads off and I've been putting it off for a long time.

Let's hope it's the lifter and not a valve or guide. Would I not be able to tell by looking at it?

You really should perform a cylinder leak down test and compression test. The compession test will check if the cylinder is still good. If you say it could have been running without firing for that long it could have scored the cylinder, broken a ring, you could have got fuel seeping by the piston and into the oil. Check the compression or have it checked first and then if the compression is good have a cylinder leak down check done. If one of the valves is burned or damaged the it will not hold compession and then go from there. If the push rod was bent or a lifter collapsed you would here alot of noise. Its awful dangerous to put anything into the cylinder to hold the valve in place. If you dont crank it by hand like 12ounce said you could lock up or break off the rope in the cylinder and then you would have real trouble. Most auto parts stores rent tools for free maybe not a compressor but try home Depot or a rental store. You shoulnt need it more then the day. You would be able to use it to check the cylinder leak down test. A little extra money now could save you alot down the road.

I have a picture or so posted of what it looks like under the lower intake manifold....
You can see the camshaft....and the lifters riding the lobes.
There is a little wheel on the end of the lifter that rides the lobe.

What is the actual symptom that the vehicle is displaying?
If the cylinder is causing a "misfire", what does the spark plug look like as compared to another cylinder's plug?
Wet, then fuel (no spark), oil then ring?, etc
Dry (no fuel)?

Also, maybe someone will have more knowledge than I.......and should correct me.........but I saw the mention of "cranking by hand" and it made me think that rotating the engine by hand (somehow....someone will need to fill that part in) with the rear valve cover off.....and watch the action of the rocker arms / valves of cylinder #1 relative to the other cylinders............

You really should perform a cylinder leak down test and compression test. The compession test will check if the cylinder is still good. If you say it could have been running without firing for that long it could have scored the cylinder, broken a ring, you could have got fuel seeping by the piston and into the oil. Check the compression or have it checked first and then if the compression is good have a cylinder leak down check done. If one of the valves is burned or damaged the it will not hold compession and then go from there.

I bought a compression guage the other day but I've never done it before and I haven't built up the courgage yet. If I understood correctily, I need to disconnect the ignition points, disconnect the plug wires and loosen the plugs. Then I connect the guage to a plug hole, have an assistant turn the key and make note of the reading, then do the same thing on the rest of the cylinders. Correct? Right now I have the upper intake manifold and valve covers off, is it OK to do this with it like that?

If the push rod was bent or a lifter collapsed you would here alot of noise.

A lot of noise is an understatement.

Its awful dangerous to put anything into the cylinder to hold the valve in place. If you dont crank it by hand like 12ounce said you could lock up or break off the rope in the cylinder and then you would have real trouble.

Yeah, I don't like the idea of putting something into the cylinder.

Most auto parts stores rent tools for free maybe not a compressor but try home Depot or a rental store. You shoulnt need it more then the day. You would be able to use it to check the cylinder leak down test. A little extra money now could save you alot down the road.

Like I said, I've allready got one, if y'all could give me any newbie tips and tricks for performing the test, that would be great.

I have a picture or so posted of what it looks like under the lower intake manifold....
You can see the camshaft....and the lifters riding the lobes.
There is a little wheel on the end of the lifter that rides the lobe.

I'm familiar with the location from when I replaced the lower manifold gaskets, I just didn't realize that's where you remove them from.

What is the actual symptom that the vehicle is displaying?

It's making a terriblly loud clicking or tapping which is in sync with the engine. It does not go away.

If the cylinder is causing a "misfire", what does the spark plug look like as compared to another cylinder's plug?
Wet, then fuel (no spark), oil then ring?, etc
Dry (no fuel)?

I changed the plugs a couple of months ago and I didn't notice anything unusual about the plugs, I don't remember any or them having fuel of oil on them. They looked burnt and dirty but these may have been the original 1998 plugs, I know the wires were and the #1 wire was nearly severed in half. The noise started after changing the intake gasket, oil and coolant.

Also, maybe someone will have more knowledge than I.......and should correct me.........but I saw the mention of "cranking by hand" and it made me think that rotating the engine by hand (somehow....someone will need to fill that part in) with the rear valve cover off.....and watch the action of the rocker arms / valves of cylinder #1 relative to the other cylinders............

I wasn't even sure if you could do that. So, if one of the rocker arms didn't move, that would identify the bad lifter?

Freakzilla
My mistake I thought you said you didnt have a compressor. Regarding the compression test. Theses vans do not have ignition points like older vehicles, they have a coil pack, and computer, no distributor. That being said you need to disconnect all plug wires to the spark plugs, carefully mark them so they dont get mixed up or disconnect the power to the coil pack. The goal is to prevent the engine from starting. Next remove a spark plug, one whos cylinder you dont expect as being bad. That will give you a base line to work from. Your compression amounts can very from as high as 250 lbs to down low as 134 lbs however from cylinder to cylinder they should be within 75percent of the others. Example 134lbs the other cylinder should be no less than 101lbs. If compression was 200 lbs the cylinder should be no less then 150 lbs. What your looking for is consistency. Ideally about 200 lbs in all cylinders. The suspect cylinder will be the one that very from the norm. If one cylinder is lower then the others. Squirt 2 tablespoons of oil in the cylinder and test again if the compression rises to the norm then your compression rings are bad. If not then the valves are suspect and the cylinder leak down test should be performed. Test method Disconnect the power to the coil pack or disconnect all wires. Remove the spark plug. Have someone crank the engine while you watch the compression gauge. The throttle should be open all the way. The reading will not jump up to its highest setting the first revolution, it will take 3 or 4 and then if it does go up it will be very little. If you want you can remove all the plugs it will make the engine turn faster.Make sure to pull the fuse to the fuel pump. That way the cylinders wont get fuel in them while checking.

The fact you now say it was making alot of noise makes me wonder if something else hasnt happend but try the compression test and post back.

Freakzilla
My mistake I thought you said you didnt have a compressor. Regarding the compression test.

I don't have a compressor, but I do have a compression guage. Thanks for the compression test advice, I might be able to get to that tonight.

Any suggestions as to how to get the oil into the cylinder (if I need to)?

I hope it's not the rings, that's probably beyond my novice ability.

Shouldn't I observe the rocker arms first to see if one obviously isn't lifting? That sounds a little easier.