Leak in head gasket


IHC in the early to mid-fifties.

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Yard Art
Yard Art

Posts: 50

Joined: Fri Jan 26, 2018 7:54 am

Location: Colorado Springs, CO

Post Sat Jun 09, 2018 12:35 pm

Leak in head gasket

I performed a leak-down test on my (new to me) BG241 - all cylinders had massive blow-by at the rings. The plan was to replace the rings, maybe rebuild the oil pump while I'm in there, and go through the head. I removed the head and found rust in #3 cylinder. All cylinder walls cleaned up good, but the rings were rusted in the grooves of #3 piston. Inspected the head and found what appears to be a head gasket leaks between #2 and #3 (would explain the rust), and #4 and #5 as well (dark areas in picture).

My first thoughts are to have the block milled (is that the right word) to make the mating surface flat and get rid of the lower area that allowed coolant through. I want to check the flatness of the mating surface on the head, and have it milled (if required) as well.

Will I create interference issues between the pistons and the valves?
Are there other options (like a different head gasket?)


Since I have the head off, my thoughts were to have the head checked for flatness of the mating surface, clean up the valves, check the valve guides, lap the valves/sets, and replace the valves seals.

Do the valve guides need to be replaced to handle todays fuels?
Are there any other thing I should be doing while I'm there?


Thanks for your help,
Heinz
Attachments
Q.jpeg
Head mating surface
W.jpeg
Underside of head gasket

Golden Jubilee
Golden Jubilee

Posts: 5170

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Sat Jun 09, 2018 1:08 pm

Re: Leak in head gasket

Ok, unless you found coolant in the cyl, rust could be from sitting with valves open.
By all mean, since you are in this far, at least check the head and block for flatness, skim cut if there is a problem. Unless you are planning on milling 1/4" off the head or block, it will be fine, it is a low compression engine by todays stds, and as long as you don't get crazy there should be no interference problems, but if you are concerned, put a little playdough on the pistons under each valve, put the head on with the old gasket and run it thru 2 revolutions and pull the head back off and measure the "squash" of the dough.
Unless you have a reason to mess with the oil pump (previous low pressure not explained by bearing clearance problems) I would leave the pump alone, it is the 1st thing to get lubed when the engine starts and the last to see lube when it shuts down, and it sits submerged in oil. I've done a whole lot of engines and rarely had a pump need attention.
If the pistons are out, remove any ridge in the top of the bore so you don't break a ring land with new rings installed, and run a hone thru the bores to get a good cross-hatch.
If there is a big ridge at the top of the bore, you need to decide if you want to re-bore or not.

Years ago, I had a Dodge 225 with over 300,000 miles that was useing a qt every 25 miles or so, As an experiment, I pulled the head, and took the ridge off, popped the pistons out and re rung with J.C. Whitney's cheapest rings, gaskets and bearings. I had less than $75 in the whole deal and oil consumption dropped to a qt in 1500 miles. The bore look more like a funnel (tapered bad) and the ring grooves on the pistons were very worn, never the less the outcome was better than I could have ever thought it could be.
Moral of the story, you don't have to make it perfect, you can fix whats wrong and get more life out of it, or you can do a complete overhaul and know you will not need to go in again, either way you make your choice and accept the outcome.
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Yard Art
Yard Art

Posts: 50

Joined: Fri Jan 26, 2018 7:54 am

Location: Colorado Springs, CO

Post Sat Jun 09, 2018 7:34 pm

Re: Leak in head gasket

Thanks for the advice CB! I don't plan to do a complete overhaul - just want to get it running, drive it for a while, and re-evaluate things. Have a loaner Piston Ridge Reamer lined up from one of the local parts stores - will ream, hone, replace rings and check for flatness of the block and head before re-assembly.

Thanks again!!!!
Heinz
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Golden Jubilee
Golden Jubilee

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Joined: Tue Dec 04, 2012 5:38 pm

Post Mon Jun 11, 2018 4:06 am

Re: Leak in head gasket

It's valve seats that are replaced to handle the new fuel , the guides I don't think matter .

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