Confirm Diagnosis, and Opinions, Please

[Steve_Mack_CT]

Put about 60 or so miles our 1939 Packard 120 today for the second time this season. About 5 miles from home I experienced rough running and power loss, almost like the car is running out of gas. Made it to a gas station a couple miles away and filled up, but about 1/8 of a mile down the road power loss seemed worse. The car seemed to run rougher and finally, on an uphill grade it seemed to lose almost all power. I could not initially restart it. So we called AAA for a lift home.

I thought it was the fuel pump but when I got it home I did get it running and noticed some drops of something being thrown from the tailpipe, and the car was still running rough with barely enough power to manouver around in the driveway. Moisture does not have much of a gasoline smell and I am thinking it is antifreeze & oil. I also see, at the back end of the block, a simillar fresh residue near the back most middle nut on the head. So I am 90% sure this is a blown head gasket. Tough to tell if the oil is "milky" or not, but I am pretty sure that the stuff the exhaust is throwing out is a mix of antifreeze & oil.

So, my questions are:

1) Is this the most likely issue and

2) How hard is it to do this job at home? It does not look terribly difficult but I am trying to decide if it is better sent out. Also, is there a better technical guide than the 1938-39 shop manual? It gives the torque specs but no torque sequence, and no dissasembly/re-assembly steps.

3) If I do decide to do this is there a recomended gasket for this car and are there any specific issues to look out for doing the job?

4) Is it necessary to remove the hood to do this?

Thanks, Steve

[Guest 1928Packard526]

Steve —

Sounds to me that you have the problem pretty well defined. You might do one other test before pulling the head. Do a compression test on all the cylinders. If the gasket has failed, (as seems most likely), the involved cylinder/(s) should show a big drop in compression pressure. It might also help identify any valve or ring problems you might not be aware of.

Since the head must come off to replace the gasket, it is an ideal time to check the flatness of the block surface and have the head machined flat again,(trued up). Only the smallest amount needed to restore a flat surface again should be taken off in that machining process. The gasket failed for some reason, and assuring these two surfaces are in good shape will help assure you shouldn't see a repeat of the problem.

Any mars or warpage noted on the block side are a different and more involved problem, but also the least likely. Check anyway.

This is also a good time to check visually that the valves and their seats are in good shape with no apparent damage. You don't want to have to pull the head again to address valve problems.

I prefer copper gaskets with the asbestos interior. These are the older style, but solid copper works well too. Both are available from several vendors. "Olson's Gaskets" is probably the best known. I'd follow their recommendations for installation. They may also be able to supply torque and tightening sequence information to fit your car.

The tightening sequence on any head I am aware of, starts at the center and spirals outward towards the ends. It is also done in several passes until the final torque is reached. The torque is then rechecked after the cars has been run enough to reach full operating temperature. I also recheck mine again after several hundred miles just to be sure everything has "settled".

Removal of the hood, while not required, certainly make working in that area easier. Less lumps on your head if nothing else.

Pete P.

[Guest Trunk Rack]

Dont forget to "re-torque" down the cyl. head nuts after one or two warm-up/cool down cycles.

All kinds of views on gasket sealer. My personal view is that if it is going to leak, it is going to leak sooner or later not matter what kind of gasket sealer you use.

The correct head-gasket for your and many older cars with "flat head" engine layout, is a "sandwich" type gasket, typically cooper "bread" on the "sandwich", with an asbestos center. Typically copper ferruls seal off the water passages and the bore. Steel, a ferrous metal, may eventually corrode in that application. Bad news if you use a steel gasket with an aluminum head, given how reactive the pre-war aluminum was. ( Somewhere I read that after analysis, one competent restore said the pre-war aluminum was so primitive & reactive he wouldn't use it today for lawn chairs! )

Yes, as some note, steel "one piece" gaskets are in wide use these days. On modern over-head valve cars, the cyl. head has considerable rigidity, so you can get away with this (assuming both surfaces are properly machined). We have a different problem with our old "flat-head" type cylinder heads. They are long and skinny, and thus are prone to flexing. The added thickness of the "sandwich' type gaskets gives you better sealing even with a head that may not be entirely true and/or warp a bit after installation.

To make matters worse, Packard's bolt/stud spacing was, in my view, a bit too wide to start with. That is why the head/to/block seal needs all the help it can get. Strongly recommend a "sandwich" type gasket as opposed to one-piece steeel.

My practice is just to spray both sides of the gasket with clean oil, put it on, and torque it down. The oil acts as a lubricant enabling the ferruls to seal the bore and water passages.

Dont forget to grease the studs if your block is so equipped, or bolts if that is the way your motor has been assembled. Sooner or later SOMEONE will have to take that thing apart again - COULD be you !

[Dave Mitchell]

This isn't a tough job, and not uncommon. I fixed one for a friend on his 40 120 last year and it doesn't take long. I have NOS gaskets if you want one. I too wouldn't use the new ones, but I would treat it with a spray on copper gasket coating. I can scan a torque sequence for you. Dave packard12s@hotmail.com

[Steve_Mack_CT]

Thanks for the information, guys.

Dave, I will email you on the gasket, and although I had some great replies on Big Kev's forum here is one more question. I believe the Packard manual calls for 72 lbs. torque but one of the old general repair manuals calls for 63 lbs. So of course I am wondering about this one, and if there is a difference between aluminum and cast torque specs.

Again, thank you all for your helpful advice.

[Owen_Dyneto]

Steve, you may be right about a Packard manual showing 72 lb-feet for an 8-cylinder head, but I've never seen anything in the Packard information other than 62-65 for the 7/16-20 threaded head nuts.

[jeff]

I plan on torquing the bolts on my head to something slightly less than the recommended torque value. Later, as mentioned above, I will re-check and go slightly higher, but still stay on the low side of the spec.

My reasoning? Today's practice is to use brand new bolts when re-installing a cylinder head. Re-using your old bolts is OK, but realize that each time they stretch a bit, and will eventually snap.

Jeff