Projects 318 engine Blow by and no compression

I put a 318 in my project car from a 86 dodge ram. Ran pretty good but had a miss. I figured it was just carb etc and blew it off and continued the swap. Now it is in my car new carb and tune up and I noticed a lot of blow by. I then did a Compression Test. 7 cylinders were all around 120 psi. Cylinder #2 is zero. I added oil to that cylinder and still zero. I used a bore scope and there is a ring from where my valve contacted my piston. Now the question I guess is can a bent valve cause blow by? Which I have always attributed to worn rings, or am I dealing with two problems. Thanks for any help.

 

An engine can be worn out, and also have a bent valve.

 

I suppose yes, but every other cylinder had 120psi and only 46,000 miles.

 

Found a busted valve spring and the valve is Shiney from hitting the piston.

 

Blow by can be caused by crank case pressure, worn rings, busted/cracked piston.

Any combination of the above. I will cost you a overhaul gasket kit to tear it down for inspection.

 

Also by a damaged guide (bent valve) Intake stroke will **** oil down that chasm like **** through a goose.

 

$30 will buy you a Leak Down tester that will tell you which part of the engine has the issues.
Put the Eng at TDC on number 1 cylinder and perform test. You dial in a (dial on left)100 lbs. of air pressure and see how much the engine is loosing (dial on right). If the rings are bad, you will hear a hiss come from the oil cap hole. If you have a bent valve or a problem in the valve train it will hiss from the carburetor or the exhaust pipe depending on intake or exhaust valve. It's the leaking air pressure from the 100 PSI that causes the hiss.
You do this on every cylinder using the rotor pointing to the cylinder being tested. Follow the firing order.
I have also seen water get push out of the rad on really bad head gaskets.
Good luck on your quest.

Cylinder Leak Down Tester Kit,Automotive Engine Pressure Gauges Compression Test Leakage Detector Tool Set (TU-21) (amazon.com)

 

I think he already knows where the problem is....but the severity of it is unknown.

Now we know it only has 46k miles, perhaps it's not worn out, just damaged. I ***umed that like all other 1986 engines, it has over 200k miles on it

 

Pull the head off and take a closer look. You may be able to replace the valve and valve spring and get it to work. I'd give it a try.

 

With a broken spring on the valve, and the valve head mark on the top of the piston, I'm betting the valve is bent. Depending or where the valve bent, I'd be concerned about the condition of the valve guide. A damaged valve guide can dump a lot of oil into a cylinder, and the bent valve would give you 0 compression.

A 318 is not an interference motor, the broken spring could have caused the bent valve, or the bent valve could have caused the broken spring, in which case the question is, "How did the valve get into the piston?"

Pull the head and have a look. you might get lucky and just need the valve and the spring and not a head. While the head is off, I'd roll the motor over to see what that cylinder wall looks like.

Broken springs on 318 heads is not a common problem, especially on a low miles motor (but not unheard of). I would want to look into the cause of the broken spring as well. It could have been a very hard 40K miles, or maybe 140K, or 240K miles.

 

I’m in the “pull the head” camp. Most of us at home don’t have to tools required to repair a bad guide, etc. in fact find a good shop and take both heads in and be done with it.
Like Gene said (***uming here that you don’t know the person you bought it from) could be any mileage ending in 40k as well.

 

You can do the same diagnostics without a leak down tester depending on your compression tester setup. We know he's losing all the air as it has no compression, so the gauge isn't needed. All he needs is a hose to pressurize the cylinder and an air compressor with an adjustable regulator. My compression tester has a hose you screw into the cylinder with a Schrader valve in the end, and the opposite end has an air chuck fitting. Remove the Schrader valve, turn down your pressure regulator, and you can diagnose where the air is coming from.

In his case, he knows it has a bent valve so he may not learn much more from that test other than if air is also going somewhere else.

 

I had something similar happen on my Buick 455. It was a 76,000 KM engine that had sat a lot. I put 2,200 km on it when it broke a valve spring, the valve kissed the piston very slightly, and it bent a valve.

I don't recall blow by, but it was running like **** so I don't know. I replaced the heads with a "rebuilt" set, and all was good for another 34,000 KM until I was having a shudder on hard acceleration. That's when I had to diagnose a cylinder with no compression (different cylinder than previous). Mine increased with oil added, which usually says rings. In my case, an exhaust valve was carboned up and stuck open. When I pressurized the cylinder, air was only coming out of the exhaust pipes. When I took the heads in, most of the exhaust seats were hammered out of it. I got both heads done and just got them back a couple weeks ago, they're not on yet.

In my case the cylinders still have a cross hatch and everything looks good.

I suggest you pressurize that cylinder if you can (30-50 psi is sufficient) and make sure there isn't air also going into the crank case (hissing from the dipstick or breathers). If not, just take the heads off and go from there.

My contact with the piston was minimal so the piston was not changed and looks fine today still. If your piston contact was more severe, you may need to change it to prevent future piston failure. After the pressure test, removing the heads is the next step.

 

You are likely seeing mostly un-burned gas and the cylinder wall in the one hole is washed out, so the rings are not sealing. Bite the bullet... take it apart. Take pictures, we like pictures.

 

Rock auto shows intake valves at $2.50 to $6.20 each. Exhaust valve is $3.50 to $10.50 (with rotator).
Your picture sure looks like an end cylinder and you mention #2, so that means exhaust. Valve picture agrees with that ***umption. Looks like no rotator, check the others to make sure someone didn't forget something.
Valve springs are around 5 bucks each, with various types listed.
A gasket set is 30 to 90 bucks. toss in oil and a tube of RTV. Reuse the filter for now.
So for around 125 bucks, you can spend some money and some effort to try a basic fix. It would be nice to at least have some lapping compound for the seat and fresh valve, or even better do them all.
A valve spring compressor should be able to be borrowed/rented easily.

Or you can grab another 318 from your local yard and swap it out with the risk of having another problem. Or just grab one head. Rock auto mentions 3 different head casting numbers. Try to match that.
Since you don't mention what it's in, I can't say how much time this is going to take, but a hoist will be a big help in the swap and not needed for the head.
It's your money and time, so it's your choice. Since you are trying to diagnose the issue on a used swapped 37 year old engine, I'd ***ume you aren't looking for a shop to swap in a rebuilt long block.

I'd agree that you should go ahead and pull the single head and inspect, unless there are other things about the current engine that are pointing toward a full replacement. As Gene mentioned, this is not a typical failure, even for a motor that has sat, provided it wasn't flooded or filled with junk. This will not affect a core charge and the engine currently together isn't worth any less partially dis***embled.
Try to get the block drain out on that side, so less coolant will get released when the head is pulled.

 

You test and test. But, you already know the problem requires dis***embly. If it were me, I'd just get to it. My guess is with blow by like you described, the piston may be broken or holed, from the vlavle contact.
One thing is dang sure....it ain't gonna fix itself

 

You should see a problem when the valve cover is pulled, I’ve seen a stuck valve cause similar problems, valve smacks. the piston and bends a push rod. All visible when the cover removed.

 

Yeah, if it was my project and the engine wasn't buried in the vehicle, I'd seriously consider scaring up a full replacement. This depends on how hard a 318 is to come by in the area.
this place has a price of 250 for a complete engine, if they have one.
https://grabandgosalvage.com/part-prices/

 

Back when I was dinkin' around with Mopars, mid 70s through late 80s, the 318 was pretty much a throw-away motor. These days, if I had one that ran good, I'd just keep it. For a driver, they're just fine. Good aftermarket heads are available fairly inexpensively, and they can be built to make reasonable power with good induction and exhaust. A good set of heads can really wake 'em up.
Sure, a 360 might make a little more power, but not enough to justify a big expense.
But if it's dead with boogered up block, crank and other internals....get another. They are plenty of 'em out there because they are not desirable max effort motors.

 

Funny story ... I had a 340 Duster years ago so I was not unfamiliar with LA engines. My uncle had a p-up with a 360 in it. Story was that he tried to start it one day and there was a big BOOM. Tried again and it started. I honestly can't remember (and he has since p***ed) if he drove it after the boom but I know it did still run. At some point he decided to part with it. I towed it home on a towbar. Once home I popped the hood and ... WOW ... the valve covers were basically unrecognizable. Seems this engine was so worn, it allowed fuel into the crankcase and the resulting BOOM ballooned the valve covers

I really wish I had kept them as wall hangers

 

Had a customer with a 318 in a cl*** B motorhome. It had maybe 90K miles and one dead hole. Somehow it ate the head of a valve and broke a hole in that piston. Against my advise, he had us put a new valve in it and one piston and rod. It ran fine. A couple of years later and maybe an additional 20K miles, he came in and was telling my service advisor that we had overhauled the engine a couple of years ago and now it is starting to use oil.

 

get a new valve, spring and lap the valve into the seat and you should be ok.

 

Is the blowby present on both banks or just the bank with the dead cylinder?

 

Maybe scroll on back up and look at Post #4. I'm pretty sure he knows what the problem is,

 

15 years ago 318s were everywhere, different story these days. Lots of the 318s that were sitting around got s****ped. The modern 5.2 that replaced the 318s are still around, but are considered a "big" motor these days, but its getting to be nearly 20 years since even those were in production. When the modern Hemi showed up in 2004, the 5.2 (318) and the 5.9 (360) became unwanted power sources again, but few are saving them these days. Fortunately you can still buy old trucks with those motors in them, but most have 200 K miles on them.

Finding a good 318 these days is about like finding a good Chevy 350, no where as easy as it used to be.

 

Main reason I'm asking these questions without fully tearing it apart is I have no real interest in tearing apart a 318 and sinking a ton of money in it. It looks to me after further inspection that the valve guide is messed up as well. My brother has a 360 in his barn that has a cam and intake he said I could buy for $300 bucks so I will most likely just swap it out. I will put this one in my barn and if at a later date I decide to tear into it I will then. This motor sat since 2006 when I got it and got it running. I'm wondering if maybe the valve was stuck and when I fired it issues arose. Either way thank you for all your replys.

 

Both

 

How do you isolate blow-by to only one bank of cylinders or the other?

 

dual exhaust and eye balls

 

Our definition of blow-by differs then. I've always considered blow-by to be burned or unburned fuel vapors that have made their way past the rings or thru a hole in a piston and gotten into the crankcase. If they escape the engine at all it's thru the road draft tube or the PCV syatem.