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A little guidance before I tear my engine apart

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RobSelina

RobSelina

Jedi Warrior
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I noticed a coolant leak on Sunday. It was a rather consistent drip, probably a drip every two-three seconds and the source was behind the exhaust manifold.

Unfortunately by the time I got the intake and exhaust disassembled (darn rusty bolts!), any coolant had disipated so I'm chasing ghosts.

I was hoping it would be a freeze plug and not the head gasket but I'm feeling pretty sure it's the head gasket at this point.

Here's a shot of the #2 freeze plug under the exhaust manifold.

mg-plug.JPG


In short, no indication of rust or leaks around the plug.

Looking at the pictures my wife took (which were much larger), I can see a hint of green along the head gasket, which is making me think that's definitely the problem but I would love to confirm it, or at least confirm that the freeze plug isn't the problem before I tear the top-end of the engine apart. Anything I can do aside from start disassembly? the oil isn't milky and I don't see any contaminants in the antifreeze either. I haven't checked compression yet, guess that might be a good thing to do?

If I need to replace my head gasket, I'm wondering what would be reasonable in terms of other preventative maintenance at the same time. Looking at the intake valves, I see a lot of buildup:

mg-valves.JPG


Car has it's original 1975 engine, with just under 50k on the odometer.

This would be the deepest I've torn into an engine, so I'm hoping someone can point me in the right direction. Any advice appreciated.
 
One suggestion - if you decide to tear it down -
- I've found that getting a sheet of cardboard & drawing a diagram of,say,the head.Draw an outline of the head,punching out holes in the cardboard where the bolts go.
That way,you don't have to figure out which bolt goes where.This also works for pushrods,oil pumps,fuel pumps,etc.
This really helps "challenged" people,like myself.
(I can't believe that I came up with this myself).
I hope that this helps you.

- Doug
 
Take lots of digital pictures as you dissassemble.
Also, put all small parts in plastic bags that are marked.

For the record, I had a freeze plug *fall out* of my 1500 while it was parked for the Winter.
It had been running fine with no leaks that year.
I opened the hood after it had been closed for about 3 months and I see one of the left-side freeze plugs laying on the ground.
Anti-freeze was "good" (not watered down).
I'm still confounded by this.
 
Re: A little guidance before I tear my engine apar

That's one I've not heard before. Very odd. Stray neutrino bombardment? /ubbthreads/images/graemlins/jester.gif

Rob: In addition to the bolts in cardboard, do the same with pushrods, et al. No "juggling" location of bits. Alternately some masking tape and a Sharpie to number them works well. And a suggestion that you clean/wash everything as you take it off (in mineral spirits). That keeps all ready for reassembly without 'surprises': "Oh, I shoulda inspected that earlier. Now I gotta order a replacement."

If you decide to do something with the valves I'd say; since this is your first go, turn the head over to a reputable machine shop. They've all the tools/machines/knowledge to do it to "spec" easily. HTH.
 
Re: A little guidance before I tear my engine apar

been mulling this over and I think I'll try to shoot for a minimal repair. Basically do the head gasket, valve cover gasket and intake/exhaust gaskets since they're all coming off anyway, clean everything as it comes out and only replace if necessary. I'd rather keep my exising valves for budget reasons, but a little cleanup couldn't hurt!

Thanks for the advice on parts organization guys, I've got no excuse for mixing them up now /ubbthreads/images/graemlins/wink.gif
 
Re: A little guidance before I tear my engine apar

Payen head gasket set from Moss on the way....
 
Re: A little guidance before I tear my engine apar

Hey Rob,

If you have not already removed your head, you may consider a more thorough inspection of your cooling system. For example, you could be leaking from the bottom of the water pump/thermostat block thing, and the water is just "finding a path" along the top of your block. Considering that your car is lower in the back, this seems possible to me.

Also, a blown head gasket is frequently accompanied by cooling problems, or water in oil, or low compression or all of the above.

While replacing the head gasket is not a bad idea anyway, once you pull the head, you open a big can of "might as well" worms. This can be very dangerous to your pocket book and your "driving season." Living in NM, you probably have a nearly year round "driving season," but nothing beats driving in spring. But if you pull your head and discover something "fishy" about one of your pistons, it could be months before you are back on the road. So, if possible, save it for the middle of summer or winter when driving is not as pleasant anyway.

Sooo... it just may be worth further inspection before you pull that head. If you can eak out another few months to a year on the engine in its current state, that will be a good thing. I am mainly speaking from my own recent, personal experience.
 
Re: A little guidance before I tear my engine apar

you're very right Morris. Now that I have the intake and exhaust bolts free and disassembly will be substantially easier next time, It seems reasonable to reassemble her and confirm that it is infact the head gasket, since I don't have the other usual symptoms.

Probably throw her back together tonight, see what happens /ubbthreads/images/graemlins/wink.gif
 
Re: A little guidance before I tear my engine apar

My local AutoZone has a "loaner" cooling system leak test kit. You basically replace the radiator cap with a special cap that allows you to pump pressure into the cold cooling system. If you have a freeze plug leaking, you should be able to see it this way. Maybe this would speed up your diagnosis...
 
Re: A little guidance before I tear my engine apar

[ QUOTE ]
My local AutoZone has a "loaner" cooling system leak test kit. You basically replace the radiator cap with a special cap that allows you to pump pressure into the cold cooling system. If you have a freeze plug leaking, you should be able to see it this way. Maybe this would speed up your diagnosis...

[/ QUOTE ]

Humm, not a bad thought. I might even be able to fab something up on the t-stat if autozone doesn't have that kit here....

What pressure does the coolant system run at once warm? about 3-5 psi?
 
Re: A little guidance before I tear my engine apar

I don't think you need to put her back together. You can do the loaner cooling system pressure test and compression check (you can loan a compression tester from Autozone, too) without running the vehicle. Putting those manifolds back on can be a real back breaker. Especially if you have the stock exhaust manifold!

I am sure you have probably already done this, but look for water droplets or choclate milk on your dipstick. If you see either of those things, the head must come off. But... if you have not been overheating, oil in water is unlikely.

I am not sure what pressure your cooling system runs at, but I think about 7psi is pretty standard for the leak test.
 
Re: A little guidance before I tear my engine apar

just picked up the compression gauge and coolant leak test kit from autozone.

Plenty to keep me busy over the weekend now /ubbthreads/images/graemlins/wink.gif
 
Re: A little guidance before I tear my engine apar

One thing that you might try is just to retorque your head bolts and see what happens, this HAS been known to stop head gasket leaks before. If you do this DON'T loosen the bolts first, just tighten them to the correct torque and see if they move.
Bill
 
Re: A little guidance before I tear my engine apar

AND DO NOT OVER TORQUE!
 
Re: A little guidance before I tear my engine apar

didn't get too much resolved tonight...

Checked compression and all cylinders were in the 110 psf range, so I'm fine with that.

Couldn't use the coolant test kit unfortunately since a hose I got didn't fit correctly. Going to try to sort that out tomorrow morning so the coolant system is closed up and then do the pressure test.

Hopefully I can torque down on those head bolts and my problem will go away! (btw, I do have a torque wrench to do it correctly)
 
Re: A little guidance before I tear my engine apar

a conclusion to this matter:

1 - I decided to retain the stock exhaust manifold for the time being. I found some goop at NAPA to seal up the crack.

2 - I did not pull the head. I had a bypass line made for the coolant system so i could omit the hard line below the exhaust manifold. After installing the line I pressure tested the coolant system to 7 PSI for probably 30 minutes. Only leak was from the hose at the t-stat housing. After replacing the hose clamp, she held pressure fine, so I resigned myself to putting it back together.

3 - the 'Payen' brand head gasket set sold by Moss is very nice. I really like the quality of their products. I replaced my leaky valve cover gasket, the intake/exhaust gasket and some of the smaller exhaust gaskets. Engine runs notably smoother at idle.

4 - after a 10 minute drive, no coolant leaks /ubbthreads/images/graemlins/smile.gif

I'll retorque all my bolts tomorrow and again in another 100 miles but I think I have this one taken care of. The only thing I can think of in terms of a leak source is that maybe a hose on the hardline was dripping down under the exhaust manifold, since that's all I've changed. I'll keep my fingers crossed.
 
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