Replaced Distributor now engine makes loud clanking.

[Awkyeow]

Ok, I am at a complete loss here as to what happened. 

First I replaced fuel pump filter. 

I also replaced the speedometer cable.

(Cable got caught under dash and I gently pulled back and forth to free it. Could I have disconnected a wire to cause this issue?) 

All this was done to replace old parts.

I replaced the coils.

I then replaced the distributor.

When I started the truck it seemed kinda ok. Idle was pretty smooth but I felt something was off. I checked the plug wires, all in the correct spots.

It acts as if it is firing off or plug wires are crossed. Idles mostly smooth. Give it gas and it has a loud clanking noise.

It ran normal before I did this.

 

I backed out and started driving.

Immediately there was clanking from the engine. I turned around, Checked timing, it was off, corrected timing to 3°. 

Still the same problem.

I then thought it was a bad distributor. Put my old one back in. Same noise. 

Rotor lines up with Intake 1 on the cap. 

 

Question. Is it possible for the oil pump shaft to move from removing the distributor? Maybe it was stuck at the connection and dropped back in just slightly off TDC?

 

The shaft is at about 11:28. Not quite 11:25. I literally just pulled out distributor and put new one in. It only goes in one way.

Any advice or knowledge would be appreciated. 

[datzenmike]

 

 

 

Has to be miss wired. Stock cap is labeled I for intake and E for exhaust. Don't assume. Easy to get two swapped.

 

Removing the distributor cannot change the spindle below it.

[Awkyeow]

I have checked 3 times. Wires are correct. 

 

[Awkyeow]

I have all the manuals, 84 service manual too.

I know how easy it is to put plug wires in wrong spot. I've done it before... lol. They are all correctly positioned.

TDC oil pump spline is positioned at around 11:28 position. Thought it was supposed to be more 11:25ish?

Distributor rotor points at the Intake 1 position. Coils are new. Plugs are less than 100 miles on them. Plug wires are old, but truck was running before with the same plugs and wires. I've check all vacuum lines. All hooked up. 

I am so confused as to what the heck happened.

[datzenmike]

Well if the wires are old pulling them off and onto another distributor may have cracked them you your observation of cross firing may be right. Doesn't take much to fire a plug at idle and almost no throttle. Put a load on it and it's harder to fire the plug(s) and the spark always looks for the easiest path to ground. If old replace them. What about the cap and the rotor??? also old???

 

I don't like replacing coils unless they are proven to not work. Stock coils are the best quality. Anything new does not guarantee that it works. Test an intake and an exhaust side plug for spark just to be sure. Replace wires first I think that will fix it.

[Awkyeow]

When this first happened I put back all the old parts, old distributor & coils, nothing changed. 

I can't find any plug wires that actually fit the 720. I honestly do not want BLUE ones.

I have purchased 2 sets in black or grey color, Both #3&4 Intake wires are to short to make it to the cap when keeping all Intake wires going down Intake side and across front of the engine to the cap.

So I did not try to swap them out.

 I find it hard to believe that the wires are the problem. But I suppose it could be possible. I WILL TRY THAT, BRB.

[NC85ST]

One way to check the wires for arcing, of course not conclusive, is start the truck at night, in the dark. Look at the distributor and the wires, do you see any arcing? It’s also possible that the clanking you hear is totally unrelated to the work you have done and you have something else going on, just a coincidence.

[Awkyeow]

Yes, this is true. The clanking could be something not related to the distributor swap.

I just find it odd that before I did this work there was no clanking and it operated good as it always has. I just wanted to replace the distributor with a new one because I wanted all parts to be replaced with newer and it has never been replaced.

As well, the engine is now a bit wobbly. It used to be pretty smooth before all this.

It is as if the engine is off just the slightest amount to still Idol 95% correct.

 

 

[Awkyeow]

Swapped the plug cables, still same issue, perhaps a tad bit better, but the clanking noise is still there under load.

Gonna replace spark plugs again just so I know that everything has been replaced with new. Uggg!!!

[datzenmike]

Internal engine noises tend to be a ticking/tapping sound or dull metallic. Clanging sound external like exhaust pipe hitting something.

 

Best plug wires are NGK color doesn't enter into it.

[Awkyeow]

Nothing is hitting anything external. Exhaust is solid, everything is solid. New. 

When engine is parked and revved the noise is slightly there. It is super loud just starting in 1rst gear and on every gear underload.

 

Truck drove fine before, parked it, worked on it, and here I am with the issue. Not sure clanking is the correct term. 

The noise is definitely coming from the engine. Internally. Perhaps very loud pinging, almost like a loud diesel engine sound. 

One odd thing is the engine sounds quieter when at Idol, the value ticking I used to get doesn't seem to be as loud. It's there during warm up but not really there after. Happy about that, just noticed the change in sound.

 

I've adjust air and Idol on carb, nothing changes.

 

It's not the plug wires, I swapped them. Same problem.

 

Could it be one of the ignition coils not firing? Perhaps an electrical issue?

Anything under the dash that could cause electrical coils issues? 

I've checked all regular fuses in fuse box.

Not the 2 big square ones. Didn't test those.

Are there any other different fuses or connections that I forgot about?

 

Nothing against the blue NGK wires, I just really do not want BLUE under the hood. Wires are not the issue.

 The only thing left is that the oil pump shaft is off. It is closer to 11:30 than 11:25 position. Though you said it can't move from distributor removal. So I'm just at a complete loss.

 

What testing can I do for ignition wires?

What about a PCV valve? Could this cause issues?

Edited May 13 by Awkyeow

[Awkyeow]

And yes,

Cap and rotor are new.

I even swapped back the old ones, nothing changed.

Both new are back on now.

 

There is one thing I did, I forgot to put the air cleaner back inside the housing before i started working on the truck... lol.

I discovered this while the truck was being worked on. 

When I took off the air cleaner cover it was stuck on. While removing, some of the insulation was pulled off from the lid and stuck around the rim of the bottom part of the housing. Is it possible some of that got inside the carb and clogged the PCV valve or something?

The Idol is about 90-95% smooth.

I am just verbally saying everything I did during this process. Whether it is prominent or not, who knows.

Edited May 14 by Awkyeow

[datzenmike]

Spindle location is fine as long as you can set the correct timing.

 

Speaking of timing, are you using a mark on the pulley as your TDC mark? If severely advanced it would ping under load.

[Awkyeow]

Correct.

Pully mark is set at 3° after warm up.

Pully mark was dead on 0 for TDC when distributor was taken off and put on.

#1 Piston was visible through #1 exhaust plug when removed.

Rotor was pointed at #1 on distributor cap.

With valve cover off, timing chain mark was lined up with #2 on cam sprocket. (After a few revolutions to get it there)

Nothing looks out or obvious to me.

 

I changed out the sparkplugs. Nothing different, but when I shut it off I noticed my coolant reservoir was really full and spouted water out the top cap for a second. Hmmm.

 

Blown headgasket?

Engine does seem hot. Much hotter than the radiator cap, and too hot for just a 15 minute idol.

 I also noticed this time and not any time prior that there was a bit of smoke or vapor coming from the tailpipe after warm up. I would have tested compression earlier, but this is the first time I've seen this.

Very odd.

 I drove it before doing the maintenance, with no issues with engine.

Also it is weird, the temp gauge doesn't go up as high as it used to either.

 

I just did a compression test.

Cylinder 3&4 have 40psi.

Cylinder 1 is at 160psi.

Cylinder 2 is 150psi.

 

Makes sense why nothing I did would ever change. Being that I just changed the distributor is why I thought timing issue.

 

I did drive it hard the last time i drove it.

How in the heck could I drive this thing with no problems, park it in the garage, do the maintenance work, start it up 2 weeks later and the engine has either a blown headgasket or rings issues.

I planned on changing out the rings, bearings and whatever possibly needed before this summer. I did compression test a few months back and cylinder 3&4 were at about 140psi. Cylinder 1&2 were about 160+/-

This recent test today #1&2 have come down about 2-4psi.

So bizarre. 

 

Could bad timing from distributor make compression that low?

Considering that everything else looks like it is correct and nothing I do changes a thing, it does make sense that the engine is busted. It's just odd. No sign of this before.

Hence why it really didn't cross my mind.

 

 Thoughts?

 

Edited May 14 by Awkyeow

[powderfinger]

Sounds like your head gasket may be blown between cylinders 3 and 4. Same place mine was blown when i bought the engine years ago. Head gasket is not a difficult job on these trucks. Although, didn't you mention you can still drive it? With a blown head gasket between two cylinders like that you should be able to crank it and move it but it should run really bad.

Edited May 14 by powderfinger

[datzenmike]

7 hours ago, Awkyeow said:

 Nothing different, but when I shut it off I noticed my coolant reservoir was really full and spouted water out the top cap for a second. Hmmm.

 

I just did a compression test.

Cylinder 3&4 have 40psi.

Cylinder 1 is at 160psi.

Cylinder 2 is 150psi.

 

 

 

I did drive it hard the last time i drove it.

 

 

I planned on changing out the rings, bearings and whatever possibly needed before this summer. I did compression test a few months back and cylinder 3&4 were at about 140psi. Cylinder 1&2 were about 160+/-

This recent test today #1&2 have come down about 2-4psi.

So bizarre. 

 

Could bad timing from distributor make compression that low?

 

 

 

Coolant reservoir over flowing and two adjacent low compression numbers is a classic sign of head gasket failure. Have you ever re-torqued the head bolts? This is the preventative for this. It's done on a cold engine, loosen ONE bolt and tighten it right away to 60 ft. lbs. Then do the next in any order you like. Do this every tune up or yearly. This keeps renew the clamping pressure on the gasket and keeps it consistent over time.

 

With compression numbers of 150-160 I wouldn't think the engine needs rebuilding for a long while.

 

Timing has zero effect on compression numbers. Two adjacent cylinders suddenly going low is a failure between them. Some of the compression is getting into the cooling system and over pressurizing it, expelling coolant into the overflow. The Z24 is known for blowing the HG at around 100k intervals.

 

Before you do anything. Do NOT remove the cam sprocket without first finding out how to secure the chain tensioner so it can't fall out. If it falls out the entire front of the engine has to come off to retrieve it and put it back. If you decide to rebuild and are replacing the timing chain, chain guides and tensioner this won't mater.

[Awkyeow]

@powderfinger It is just strange that the truck ran fine with no sign of engine issues.

I parked it, pulled distributor, changed a fuel pump filter and speedometer cable.

Started it up and it was like this. That is why I thought it was a timing issue or something. No smoke or anything. It drove with a loud knocking noise so I have not driven t much, just around the block or so, just a few times after I swapped items to test if that was the issue. Only the last time I noticed smoke or more like vapor when idoling in the garage. I then did a compression test. 

Gonna rebuild the entire engine. Was going to anyway. Had lower compression on Cyl 3&4 about 2 months ago. Squirted oil in the cylinders and the pressure went up, so I assumed rings, not headgasket. 

 

@datzenmike

I replaced a blown head gasket in 1997 or 98.  Replaced rings, timing chain/tensioner etc. in 2004 or 05. So it's been almost 20 years.

No I never re-torqued the head bolts.

I will this time.

This will be the second time the head gasket has blown since 1989.

 

I am going to replace everything. 

 

Is it still OK to shave the head a 2nd time? Or should I source a new/different one?

Much appreciated with all your advice as always.  ALL OF YOU!!!

 

A blown head gasket was the last thing I thought it would be.

I will take this as a WIN!

It's an answer. Finally.

Edited May 14 by Awkyeow

[powderfinger]

If it was me I would fix the head gasket and drive it.

[Awkyeow]

That is exactly what I plan to do.

Though, I am going to replace other things while I am in there.  It is time.

Are you suggesting to ONLY repair the head gasket?

[datzenmike]

4 hours ago, datzenmike said:

With compression numbers of 150-160 I wouldn't think the engine needs rebuilding for a long while.

 

 

 

Yes. replace the head gasket is all you need.

 

FWIW: the head only gets shaved if it needs it, otherwise waste of money. It only needs this if sightly warped. Put a straight edge across it in an X and down both sides. If you can slip a 0.004" feeler gauge under it at any point then you can have it shaved. 0.004" is about the thickness of newsprint. 

 

[ElliotV]

13 hours ago, powderfinger said:

Sounds like your head gasket may be blown between cylinders 3 and 4. Same place mine was blown when i bought the engine years ago. Head gasket is not a difficult job on these trucks. Although, didn't you mention you can still drive it? With a blown head gasket between two cylinders like that you should be able to crank it and move it but it should run really bad.

I think between 3 and 4 are the only two places I have read of it being blowing out. Even the 86 I picked up a couple months ago the guy that was where it was blown and he even drove it before he replaced it and it was just gutless and ran bad.

[datzenmike]

Two and three are the middle of the head and most likely if the head warps. (it only warps from drivers ignoring the temperature gauge) My L20B in my 620 blew out to the spark plug side on #3. Found nothing wrong other than the gasket.