Another Blown Head Gasket!

[turtle1173]

This 1972 Chrysler 85HP had a blown head gasket when I got it (of course I didn't know it when I bought it). I replaced the head gasket and have been working on it for the past couple months. Today I finally got it to run in gear but it didn't have much power and was blowing white smoke. Upon pulling the plugs, it was clear that some water was getting into the #1 cylinder. I pulled the head and the gasket was blown. This occured with about 15 minutes of "in gear" running.<br /><br /> I want to know if this would be caused by some restriction in the cooling circuit or something else. My manual talks about a water pressure release valve that, if stuck, would put excessive pressure on the system and would come through at the weakest point. Do you think this is a possiblity?<br /><br /> I hate to even think about this but do you think I need to take the exhaust manifold apart and check these passages?<br /><br />Thanks,<br /><br />Shane

 

[Solittle]

Re: Another Blown Head Gasket!

Did it get real hot? How long since the water pump was replaced?<br /><br />I wouldn't pull the ex manifold just yet.

 

[turtle1173]

Re: Another Blown Head Gasket!

No, it didn't get real hot. It was pumping water the whole time but it wasn't pumping as much when it was in gear. I was afraid to do much with it because of low power and excessive white smoke. I replaced the water pump 3 weeks ago.<br /><br />Shane

 

[jim dozier]

Re: Another Blown Head Gasket!

Did you check the cylinder head for flatness before you reinstalled it? Did you torque the head bolts to the proper specs in the proper order?

 

[turtle1173]

Re: Another Blown Head Gasket!

I didn't do anything special to check it for flatness other than to just look it over. I did torque everything according to the manual.<br /><br /> Are you inclined to believe that the head is warped instead of there being a restriction somewhere?<br /><br />Thanks,<br /><br />Shane

 

[jim dozier]

Re: Another Blown Head Gasket!

Head gaskets usually blow or fail due to:<br />1. Overheating<br />2. Warped head or block mating surface<br />3. Nicks in mating surfaces<br />4. Incorrect torque or torque sequence<br /><br />I could be wrong but I don't think excess water pressure would blow the head gasket. Cylinder pressures during the firing cycle would be orders of magnitude greater than water pressure and the gasket is designed to withstand the cylinder firing pressure.<br /><br />The only way a coolant restriction would blow the head gasket is if it caused the engine to overheat which is number 1 on the list above.

 

[jim dozier]

Re: Another Blown Head Gasket!

Add to the list. If your engine is badly timed and you are firing the cylinder too advanced and you get detonation this will overpressure the cylinder and increase the likelyhood of gasket failure. I would think that it would take more than 15 minutes of this though.

 

[turtle1173]

Re: Another Blown Head Gasket!

JimD, thanks for the explanation about the causes for head gasket failure.<br /><br /> Let me run this by you. The head gasket was blown when I got this engine (I didn't know about it then though). With all the work that I've done to the engine it seems obvious that the engine had overheated (some cylinder scoring, a very discolored head, and a couple of tangs (is that what their called) missing off of the water pump).<br /><br /> I don't know if this is the original head on the motor or not. It probably is but it is more brown in color than white. I suppose that it is likely to be warped some. Interestingly enough though, the exhaust manifold looks brand new with no discoloration whatsoever.<br /><br /> What concerns me (and I guess no one will have an answer for this) is what caused it to overheat the first time?? If the head was initially fine but overheated and caused the discoloration, it may be warped now but was it that way already? It is also obvious that the previous owner was trying to patch things up to make it work because Permatex was spread everywhere on the head.<br /><br />Any thoughts or should I just get the head flattened at the shop and try it again??<br /><br />Thanks,<br /><br />Shane

 

[jim dozier]

Re: Another Blown Head Gasket!

Based on your description, the missing impeller vanes almost certainly caused the engine to overheat as evidenced by the discolored head. This probably wasn't a one-time overheat either. The overheat caused the first gasket to blow and warped the head (I'm guessing on the warp). You replaced the head (probably warped) which didn't seal and blew out the gasket the first time you fired it up. One would hope now that you've fixed the cooling system, rebuilt the carbs, and machined the head and properly reinstalled it, you'd be good to go.

 

[turtle1173]

Re: Another Blown Head Gasket!

That sounds like a very probable scenario.<br /><br /> Ah yes, "impellar vanes" is what I couldn't think of. Oh well, you knew what I was talking about <br /><br /> I'll have to get this head up to the machine shop and see what they have to say about it. Unfortunately one of my head bolts broke when I was re-torquing the head yesterday (before I removed the head), so I'll have to get that taken care of also.<br /><br /> When it rains, it pours!<br /><br />Thanks for all your help.<br /><br />Shane

 

[Yepblaze]

Re: Another Blown Head Gasket!

Tang it!<br /><br />Iffin you didn't retrieve all the extra water pump impeller "tangs" it's possible that one is lodged in the water tube or passage somewhere and will continue to haunt you with overheating till it's found and removed.<br /><br />I'm not saying this "Has to be" what's wrong but a "what if?"<br /><br />Smoke is one thing, but steam is white and smokelike. Apartialy flowing colling system might provide enough flow to steam well.

 

[SeaMasterZ@aol.com]

Re: Another Blown Head Gasket!

put the head on some plate glass ... get a small piece at the hardware store, that way you can check the head and the cylinder deck to determine flatness<br /><br />if warped ... milling the head will boost compression, so make sure you do a compression test, if its on the high side of the specs, might want to run hi test, run mid grade at all times if not, its worth the few pennies <br /><br />and at repower time ...<br /><br />O M C <br /><br />

 

[turtle1173]

Re: Another Blown Head Gasket!

I did find both of the missing tangs. Tangs for the suggestion though <br /><br /> I like the idea about the plate glass. I might just go ahead and take it to the shop though.<br /><br /> How will mid-grade affect the compression?<br /><br /> I've already promised myself numerous times that I will never get another Chrysler. Of course I said that before I bought this one but I thought I got a great deal <br /><br />Tangs again!<br /><br />Shane

 

[SeaMasterZ@aol.com]

Re: Another Blown Head Gasket!

mid grade wont affect compression, it will affect how it runs under load<br /><br />all outboards should run mid grade, unless they are race mills .. <br /><br />regular is crap, has no cleaners in it, ugh, run lawn mowers and chevy impalas on it (well, MY chevy impala anyway, lol)<br /><br />Im not a boat mechanic mind you, Im an ex - car mechanic<br /><br />but think about it<br /><br />boats run under load ALL the time, there is no hills to coast down, no overdrive to loaf along at 1800 in ... its cranked up, under load ALL the time (cept no wake areas, well, if someone is around to see )<br /><br />its like running up a grade all the time<br /><br />know how your car likes to ping going up a bridge or mountain? (like mine on regular gas does!)<br /><br />pinging is bad, its a ping cause its encased in steel and coming thru the sound insulation under the hood<br /><br />in the cylinder, its a violent, ill timed explosion that loads up the piston, the rod and the bearings, the crank is pretty beefy, it takes the hit without too much of a problem<br /><br />but<br /><br />your head gasket is right there, ground zero, and IT is taking the hit<br /><br />so use the better stuff, yer engine will love ya for it<br /><br />and if you mill it ... well, thats gonna raise the compression, but usually they just clean it up, .05 or so<br /><br />good luck, chrysler or not, a sweet running 85 is a gooooood fishin buddy when you hear the fish are biting at the other end of the lake / bay / whereever<br /><br />

 

[SeaMasterZ@aol.com]

Re: Another Blown Head Gasket!

Exception: <br /><br />unless its a lawn boy mower, two cycle, ex OMC, it deserves good stuff too!

 

[jim dozier]

Re: Another Blown Head Gasket!

The machine shop will usually not take more than 0.005 inch, that's 5 thousandths of an inch Castaway not 0.05 or 5 hundreths. If you do the calculations 5 thousandths won't raise the compression much. I had to have 40 thousandths removed from my Honda (car) to raise it from 9.2 to 10.2:1. Most 2-stroke outboards are relatively low compression to start with. If they have to remove more than 5 thousandths to flatten it out I would look for another used head and have them work on it. They are probably available at a used parts depo somewhere. Personally I don't have a problem with 87 octane regular unleaded.

 

[turtle1173]

Re: Another Blown Head Gasket!

I just wanted to give everyone an update. I took the head to a machine shop this morning. I asked him if he thought it was warped and told him the problem I was having. He pulled out a small straight edge and held it up there against the head. He said it was definitely warped and thought it was the problem. You could see the light under the straight edge as he moved it across it. Cost will be $35-$40.<br /><br />Shane

 

[93bronco]

Re: Another Blown Head Gasket!

i had two omc 120/140 heads done @ 25 each <$50>. had to take them down 10ths. was told by some on this forum its would be ok. the book says you can take 5 from head & 5 from block, so i guess it should be fine with only 10 total.

 

[echozulu]

Re: Another Blown Head Gasket!

chrysler motors made of tin ride em out paddle em in

 

[SeaMasterZ@aol.com]

Re: Another Blown Head Gasket!

I hope that wasnt his special " see, that thar sum***** is warped!" straight edge, lol<br /><br />teasing, sounds like a good deal<br /><br />EZ, shame on ya, paddle em in ... <br /><br />chrysler motors really blow, <br />ride em out come in on a tow!<br /><br />of course, I would settle for a running chrysler rather than my fleet of busted OMC at this point!!!