340 coolant in oil

[Milkman]

I have a 71 Dart with a 340. It is running like it is only firing on a few cylinders. I noticed a white/greyish sludge on the dipstick and so I assumed the head gasket was blown. I pulled the head and the gasket looks fine. Just looking at the head, it looks like it is fine with no cracks. Does anyone have any ideas, I am a novice and would appreciate any advice. I put a picture showing the gasket intact.
Thanks!

 

[Rodsaknockin]

Take your head to a local machine shop and have them magna flux it and he will or should be able to tell you right away if there is a crack takes 5 minutes

 

[jaws]

How was the intake gasket?

 

[xLURKxDOGx]

A timing cover leak can cause it as well, something to look into.

Jake

 

[Garrett Ellison]

Check and see if you have any plugs that appear to be steam cleaned on the left hand cylinder bank, you may have pulled the wrong head. Has it been losing coolant or have air bubbles/positive pressure in radiator, and do you have a bulk of water when you drain oil? Any overheating? I still would have the head you pulled magnafluxed, though. A compression test before teardown may have helped, and you may be able to run one on the left bank, but you'd want to temporarily plug the rocker oil supply on the right deck before running one as well as catchwhat comes from the fuel pump. Set up a jumper wire with push button switch to the prong on solednoid with yellow wire, this will let you crank over with starter without the ignition turned on.. having the valve seats and guides checked on the head you pulled may be in order as well. It's entirely possible that if it's just a little sludge with no coolant loss it could be condensation, but only if you live in a high humidity area. Is the underside of the gasket intact as well?

 

[Inertia]

When you pulled the dipstick, was the crankcase oil on the end of the dipstick milky, or was it the usual brownish, with traces of sludge on the upper edges of the stick above the oil ?
If the oil isn't milky, it is more likely just condensation accumulation inside the engine from driving short trips, or the PCV system needs attention.
Were the inside of the valve covers sludgy as well ?

 

[MoparLeo]

First, get a service manual. Second, clean up that mess. How can you possibly see any problems, especially if this is your first ( probably) engine tear down with everything in the way. Drain the coolant from the lower hose and probably the block drains. Be careful where you put the coolant. Poison you know. As said before. Take the heads to a machine shop that does engine work to be tested for cracks ( Magna-flux) warpage and possible time for a valve job. Get organized. Internal engine work is like internal human surgery. Clean, and organized or your dead. Find someone with some engine experience and tools. Prepare to spend some money before you get started so you don't tear it apart and then change your mind. Lot of people do that. Know what you are getting into.

 

[rustycowll69]

I have a 71 Dart with a 340. It is running like it is only firing on a few cylinders. I noticed a white/greyish sludge on the dipstick and so I assumed the head gasket was blown. I pulled the head and the gasket looks fine. Just looking at the head, it looks like it is fine with no cracks. Does anyone have any ideas, I am a novice and would appreciate any advice. I put a picture showing the gasket intact.
Thanks!View attachment 1715276232

I think pulling this engine apart before thoroughly diagnosing the symptoms and causes was probably a mistake. what little I can see in the pic does not look bad. I can't see all of the valley, but it does not look sludgy. The coolant looks relatively fresh. Like one poster asked, was the dipstick fully covered with a chocolate milk shake goo? or just the part above the fill line. You may have conflated some condensation sludge from short trips or lack of driving, with a miss from bad gas, or bad spark plug or wires. They may not even be directly related. If it had no history of overheating, why would you assume a blown head gasket?
this is not a late model all aluminum engine which blows a head gasket the first time it overheats.

 

[MoparLeo]

Yep. Pulled the trigger a little too soon I think.

 

[Milkman]

When you pulled the dipstick, was the crankcase oil on the end of the dipstick milky, or was it the usual brownish, with traces of sludge on the upper edges of the stick above the oil ?
If the oil isn't milky, it is more likely just condensation accumulation inside the engine from driving short trips, or the PCV system needs attention.
Were the inside of the valve covers sludgy as well ?

The oil was milky white the whole length of the dipstick. Some of the sludge was closer to the top.

 

[Milkman]

How was the intake gasket?

Intake gasket looks good. There is also milky white substance on the inside of the valve cover.

 

[4spdragtop]

Coolant in cyl 2 and 4 is from you spilling? You could have pulled oil pan drain plug to check for water. Cracks arent always visible with the eye.
Good luck

 

[Garrett Ellison]

Yes, good luck, and as per MoparLeo, plan on a half a day of getting all the coolant drained, hoses and wiring and fuel lines out of the the way, and the mess cleaned up before going any farther. Looking at the condition of the front cover, that's where I would suspect coolant loss as well. How much coolant were you losing?

 

[416stroker]

Possible crack in the block along the deck? I had a 340 that had 2 barely visible hairline cracks leading from the lower head bolt threads to the cylinder between the first and second bore.

 

[nm9stheham]

Why pull the cylinder head just one side? Pull the other one now. If you suspect a leak in the head(s), then have them pressure tested rather than magnafluxed. Also, have them checked for flatness on the bottom surface; you're looking for warpage.

Next step after soaking up all that coolant in the cylinders with paper towels and getting it out of there pronto, turn the crank around and around to push all that coolant up where you can get it ALL out. Then spray the cylinder with WD40 as a temporary measure to protect them.

Drain the oil and examine it.... which should have been step #1. See if it is milky through out and, when you pull the plug, watch closely for the first liquid that drains out and see if any coolant comes out first.

Realize that any leak could be anywhere touched by the coolant.

BTW, I can't quite see the fan well enough. Get rid of it if it is a stainless bladed flex fan. The blades develop cracks near the steel spokes and can eventually fly off and destroy things like radiators.

 

[Milkman]

Why pull the cylinder head just one side? Pull the other one now. If you suspect a leak in the head(s), then have them pressure tested rather than magnafluxed. Also, have them checked for flatness on the bottom surface; you're looking for warpage.

Next step after soaking up all that coolant in the cylinders with paper towels and getting it out of there pronto, turn the crank around and around to push all that coolant up where you can get it ALL out. Then spray the cylinder with WD40 as a temporary measure to protect them.

Drain the oil and examine it.... which should have been step #1. See if it is milky through out and, when you pull the plug, watch closely for the first liquid that drains out and see if any coolant comes out first.

Realize that any leak could be anywhere touched by the coolant.

BTW, I can't quite see the fan well enough. Get rid of it if it is a stainless bladed flex fan. The blades develop cracks near the steel spokes and can eventually fly off and destroy things like radiators.

I pulled that side first because I would hear a hissing sound coming from the area of that head and it would last about 10 seconds after the motor was shut off. I appreciate everyone’s help and suggestions.

 

[nm9stheham]

That is certainly logical.

Can you tell us any more about the poor running prior to pulling this head? Was the motor running hot as indicated on the temp gauge?

 

[Milkman]

That is certainly logical.

Can you tell us any more about the poor running prior to pulling this head? Was the motor running hot as indicated on the temp gauge?

The motor was running normal temp. It seemed to run ok until it warmed up, then it began to misfire badly and had no power. It also sounded different as if it was only running on 4 cylinders. It also would die at idle. There was not any smoke coming from exhaust.

 

[Garrett Ellison]

The motor was running normal temp. It seemed to run ok until it warmed up, then it began to misfire badly and had no power. It also sounded different as if it was only running on 4 cylinders. It also would die at idle. There was not any smoke coming from exhaust.

What kind of intake does it have? It’s rare, but I have seen an intake crack through the exhaust cross over into the plenum under carb and cause what you described. It may merit a pressure test on exhaust heat crossover passage in manifold as well...

 

[furrystump]

Make sure the fire rings are still round. La’s tend to push the head gaskets into the valley. Thats why on the r blocks they have a provision for a fifth head bolt.

 

[nm9stheham]

Make sure the fire rings are still round. La’s tend to push the head gaskets into the valley. That's why on the r blocks they have a provision for a fifth head bolt.

I keep looking at the OP's pix and they look round.. But the view is so far away, that it is hard to tell. OP, it might help if you could post close ups of the head gasket, perhaps 1 of the front 2 cylinders and another of the back 2 cylinders.

Also, could you post a pix of the bottom side of that head that you removed?

What kind of intake does it have? It’s rare, but I have seen an intake crack through the exhaust cross over into the plenum under carb and cause what you described. It may merit a pressure test on exhaust heat crossover passage in manifold as well...

Which points out that it could be quite a number of issues.

 

[Milkman]

What kind of intake does it have? It’s rare, but I have seen an intake crack through the exhaust cross over into the plenum under carb and cause what you described. It may merit a pressure test on exhaust heat crossover passage in manifold as well...

 

[Milkman]

It has a cast iron intake, would anything be visible to the eye? There is no sludge in the lifter valley but you can see a small amount of coolant in there.

 

[Garrett Ellison]

Only if it were directly under carburetor, if that coolant didn’t come from manifold end port during removal and it appears to have been there a while, dry it up. Look for cracks in the valley and deck relative to that point and check the bottom of the head gasket and cylinder head at that point as well. I won’t say for certain but I believe you are on the right track, check the coolant crossover passages under the manifold as well. I am hoping that it is something as simple as the manifold, I have known of more than one to have had trouble. I know I hate finding cracked decks or cylinder heads...

 

[Milkman]

I keep looking at the OP's pix and they look round.. But the view is so far away, that it is hard to tell. OP, it might help if you could post close ups of the head gasket, perhaps 1 of the front 2 cylinders and another of the back 2 cylinders.

Also, could you post a pix of the bottom side of that head that you removed?

Which points out that it could be quite a number of issues.

Here are a few more pictures. I’ve noticed number 4 cylinder has some minor pitting, from what I assume is coolant sitting in there?