another tip

Mon Dec 22, 2003 10:51 pm

If the head bolt holes pass through to the water jacket, instead of oil use teflon pipe dope (liquid - not tape!) on the threads. I've rebuilt a few engines, and I was given this tip by an auto mechanic friend. You'll never have a problem with fluid leaking into the head, and the threads don't get crusty & come out nicely if you ever have to take it apart again.

I coat all my gaskets with anti-seize. Messy, but they seal fine & don't stick when you take things apart.

Never re-use a head gasket. (my $0.02) I would also recommend using new bolts every time you bolt the head on. Torque in steps. 15, then 30, then 40, then 45 ft/lbs. Follow the same pattern each time.

Poor-man's magnaflux leak/crack checker:

- Clean block surface with brake cleaner

- Spray with #2 fuel oil (diesel works but fuel oil has red dye in it)

- Allow to soak for a while.

- Wipe clean w/rag dampened with brake cleaner

- put some corn starch in a piece of cheese cloth, and pat over surface. Coat with a thin layer of corn starch.

If you have a crack, the corn starch will pull the fuel oil out of the crack, and it will turn it red.

Hhmm, come to think of it I can't remember - was it corn starch, or talcum powder? :? Anyway, I suppose either would work.

Tue Dec 23, 2003 12:09 am

:) Hey Scott, I like your Poor-man's magnaflux leak/crack checker:
Never heard of that trick before.

Tue Dec 23, 2003 12:56 am

I went back to the shop where I had my cylinder head resurfaced to get a new gasket and I explained my situation. He reinerated alot of what you all told me. He had a gasket, but suggested that I try some things first. He said to take out one bolt at a time(in order), wire brush it, soak it in oil, put oil on the top surface of the head where the bolt head seats, retorque it to 45 ft lbs, then do another until all 15 are done. Also anywhere a bolts hits water (#5 bolt) use a silicone thread sealer. He also said he retorques many times before he sends his engines out and even when he uses a copper sealer sometimes it bubbles the first time.
I followed this procedure and ran my cub. I had a little bubbling but only a fraction of the previous time. I let it run a while and retorqued (45) and it sealed. I let it cool down, ran it hot again then checked the torque a couple more times and everything is fine.
Thank you all for your knowledge to get me through this unfamiliar task. Now George, I have something just after I needed it - experience !

Roy

Tue Dec 23, 2003 8:53 am

I have been watching this thread but nowhere has any body said anynthing about checking the deck of it for flatness.
I have seen & so have some of you other guys when the head is warped the block sometimes does to.

As for putting somthing on the head gasket (antisez.) (grease)
I worked in a garage for 12 years & the only head gasket you put any thing on was some of the mopars.

If I hired you to put a engine to gether for me & you put somthing on the head gasket you would get to do it again for free witth nothing on it .
Between I and my father we have over 75 years of rebuilding motors and
as I stated earler we only put a sealer on those that stated to do so.

One last thing on this tread how much did you have the head milled &
did you cmpensate for it in the head gasket.
In a l block valves are in the block if you remove to much off the head & don't replace it with somthing you will bend valve.

Sorry I don't mean to preach but why spend money if you don't have to on a 2nd rebuild.

Rule #1 on a rebuild check everything out then check it again.
replaceing a head or head gasket rule #1 still applies
Dale51

Tue Dec 23, 2003 10:40 am

Roy wrote:I went back to the shop where I had my cylinder head resurfaced to get a new gasket and I explained my situation. He reinerated alot of what you all told me. He had a gasket, but suggested that I try some things first. He said to take out one bolt at a time(in order), wire brush it, soak it in oil, put oil on the top surface of the head where the bolt head seats, retorque it to 45 ft lbs, then do another until all 15 are done. Also anywhere a bolts hits water (#5 bolt) use a silicone thread sealer. He also said he retorques many times before he sends his engines out and even when he uses a copper sealer sometimes it bubbles the first time.
Roy


Roy,

Your mechanic may not be aware of it, but ALL the head bolts enter the water jacket :!: I prefer to coat all the threads and the under side of the bolt head with plumber's teflon pipe dope. While others may disagree, I recommend you do the same... one bolt at a time. You decide.

I have been watching this thread but nowhere has any body said anynthing about checking the deck of it for flatness.
I have seen & so have some of you other guys when the head is warped the block sometimes does to.


Dale,

You may have forgotten, but the Cub has a flat head engine. Both surfaces should be checked for damage, but neither can possibly warp enough to matter. That thin little head will conform to the block like it was made of rubber :!: Valve clearance is not affected by decking or milling on a flat head. :lol: :lol:

correction

Tue Dec 23, 2003 9:56 pm

What I meant to say was "I use anti-seize on all my gaskets EXCEPT head gaskets."

All the instructions I have ever seen said to install a head gasket only between clean, dry surfaces with no additional sealant or lubricants. I have never used any kind of sealant or lubricant on any engine ever, and I have never had one leak.

**Disclaimer** I have never rebuilt a cub engine, although I can't imagine it is that much different from any other engine I have worked on.

The more I learn, the more I find there is more to learn. :wink:

Tue Dec 23, 2003 10:13 pm

Thanks George
All the bolts threads and bolt heads are now coated with sealer. I ran my cub after several times and the torque was 45 and no leaks.

Roy

Wed Dec 24, 2003 9:48 am

Politically speaking

Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


Usually if you have a maximum clearance of 0.0001-0.00015 (flat surface) between the engine block deck and the cylinder head, a specified cylinder head gasket for that engine with no sealant (if not specified) should seal with no coolant seepage.

The critical part of the seal for the engine block/cylinder to the engine head gasket seal at the gasket is just outside the engine cylinder envelope. At that point you will notice the head gasket will have a metal band completely circled. If that part of the engine block to engine cylinder head is not with in specs, no sealer or gasket cement (that I know of) will stop compression seepage.

It’s a little different story around the coolant passages on the rest of cylinder block deck to the cylinder head. The only thing you have to overcome is the coolant system pressure as engine temperature rises. Sometimes that can be compensated with sealant or gasket cement.

On most of todays engines (that I know of) the cylinder head gasket is put on dry and the head bolts are tighten by the “torque to yield” method and the head bolts are sealed with “threadlocker”. This is done because the people who designed the engines determined the fasteners stretch when you apply torque to them.

I had a customer complaint of a coolant system overheating issue on a 02 vehicle within the factory warranty peroid.The problem was verified by a cylinder head gasket seepage by a head bolt. I remove the engine head and everything was to factory specs. The factory determined to replace the head gasket and recheck. The customer came back within a short period of time with the same complaint and the vehicle was given to another technician to see if I overlooked anything. The factory determined again to remove the engine head and recheck. Nothing again was found and engine was reassembled. The vehicle came back with same complaint in a short period of time again and the factory was faced with the “lemon law”. At that time it was determined to add a coolant system supplement to see if that would help. The vehicle did not return within the warranty period for the same issue.

However I did find out the vehicle had a coolant issue again (with the head gasket) when the vehicle was out of the factory warranty. The vehicle was taken to a non factory shop (independent shop) for repair. It was found one of the cylinder head bolts was made to long. What was ironic about the whole thing was,everytime the cylinder head was removed a new set of cylinder head bolts was required per factory specs. The one head bolt in that spot was one certain length and was not applicable to any other spot.

As you would expect the owner wants compensation and the factory is objecting since the vehicle is out of warranty.

The moral of the story; Experience is something you don't get until just after you need it. :!: :!: :!:

:arrow: That’s why I listen (read) everything on the forum.
Jack Fowler