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Coolant in oil...cracked block?


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I was running my '31 8-86 a couple of days ago, trying to adjust the carburetor, when I noticed steam coming out of the crankcase vent and valve cover. That doesn't seem right.

 

Upon examining the oil, I've got a fair bit of coolant in there. I immediately suspected the head gasket. I drained the coolant as well, but noticed no oil to speak of there; not sure if that's indicative of something.

 

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My friend graciously helped removed the head last night, which revealed a pretty good looking head gasket. It also revealed that someone dumped in some sort of stop-leak, from best I can tell. Lots of blue gunk coating every surface that coolant runs through.

 

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It also looks like someone coated some of the head bolts in silicone, for some reason. I noticed that the top surfaces of the head where some of the silicone-coated bolts screw through were looking chewed up. Not sure what to make of that, either.

 

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Cylinder walls look okay to my eyes, with some of the pistons having a little more slop than others. I assume the rings take care of that, though. 

 

How should I proceed in tracking down where the coolant is getting into the oil? I haven't taken the oil heat exchanger off yet, though I would've expected a good mix of oil and coolant in the radiator, too, if the leak were there, right? 

 

If I do have a cracked block, how can I plug the coolant ports to verify? 

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Here's a top-down of the pistons, after a little bit of cleaning with a rag. The piston second from right was very easy to clean, so I wonder if it was getting more coolant into the chamber than others, freeing up more of the carbon buildup. Not sure. 

 

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That same piston, before cleaning:

 

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The head only had two—well, two and a half—studs stay behind. One was sheered off before I got the breaker bar after it. Wonder how long it had been broken, as the rest of the stud was still hanging around. 

 

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Drovak,

    You will see sealant on the threads of the head bolts because some of them penetrate into the cooling jacket.  The small  heat exchangers on the side of the engine are notorious for leaking coolant into the oil.  Most restorers have removed the small "radiator" and bypassed with copper tubing inside the housing.

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1 minute ago, Mark Shaw said:

You will see sealant on the threads of the head bolts because some of them penetrate into the cooling jacket.  The small  heat exchangers on the side of the engine are notorious for leaking coolant into the oil.  Most restorers have removed the small "radiator" and bypassed with copper tubing inside the housing.

Great info, thanks! I'll dig into that heat exchanger in a couple of days. What's the easiest way to disassemble that side? Can the generator and water pump stay in place for this operation?

 

Happy Thanksgiving!

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You can remove the heat exchanger without removing the generator or water pump. cut the radiator hose between pump and heat exchanger land disconnect the two lines at the engine block, not he connectors on the exchanger.  remove the two bolts that mount the exchanger to the block. the unit should come out with an upward motion to come free of the connectors at the bottom.  

 

I have seen cracks between valve seats on a number of heads.  I have seen cracks in the block water jacket behind the lifter galley.  I hope you find your problem is the heat exchanger as that is a simple fix.

 

Bob Engle

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Mr Engle is correct. My 1929 has freeze plugs behind the lifter covers. They are prone to rust through which yields coolant in crankcase oil.

I might have removed all spark plugs and left oil drain plug out while pressurizing the cooling system to determine the source of the leak.

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Excellent. I'll check the heat exchanger soon.

 

Where do you guys recommend getting a gasket set for this engine? While I have things apart, I'd like to replace every gasket I can. 

 

I noticed that the exhaust manifold gasket failed. Is this a common problem with these copper gaskets? Is there a specific gasket material recommended for longevity?

 

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Also, for things like new intake/exhaust studs and head bolts, is there a vendor that sells these, or should I plan to get them made at a machine shop?

 

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In other news...has anyone seen 28 AWG magnet wire used instead of steel safety wire before? I think there's a reason aircraft mechanics don't use copper!

 

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In other other news, what's this broken spring for attached to the cover for the (still invisible) timing mark?

 

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Also, am I missing any literature for working on this car? I thought the manuals would have more in the way of step-by-step instructions for removal and assembly of various things, but that's not the case. My MGB shop manual is far more detailed, but perhaps people just inherently knew what they were doing back in the '20s and '30s!

 

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It looks like you have the same books as I do and like you I wish they had more detail and step by step instruction. I have heard the later books are better and may help with the 31, I am still looking. I think the writers presumed we are already trained Buick technicians!

 

I have been using Olson's for gaskets. Very good people and high quality product.

 

Dave 

 

ps Don't loose track of the special washers on the exhaust manifold they are critical and the new ones you can buy are very thin.

Edited by Dave39MD (see edit history)
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I inspected the oil heat exchanger, and there is indeed a leak between the two sides. However, I'm not sure that explains everything, like why cylinder 7 had evidence of more coolant than the other cylinders, or why there was zero oil in the coolant. Nevertheless, I'll be bypassing the heat exchanger soon.

 

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In reality, there are only two places that oil can get into the coolant: 1 is the heat exchanger which you have taken apart.   2 there is a short oil passage in the cylinder head for oil from the filter enters and then exits into the rocker arm shaft.  the second one is highly unlikely.  You have addressed the first.  

 

Coolant can get into the oil from a cracked cylinder head, the heat exchanger, a cracked block, and cylinder head bolts.

 

Bob Engle

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59 minutes ago, Robert Engle said:

In reality, there are only two places that oil can get into the coolant: 1 is the heat exchanger which you have taken apart.   2 there is a short oil passage in the cylinder head for oil from the filter enters and then exits into the rocker arm shaft.  the second one is highly unlikely.  You have addressed the first.  

I am trying to understand how I have a clear leak in the heat exchanger (tested by lightly pressurizing the oil side with the exchanger submerged in water, with bubbles clearly coming out from the coolant side) yet have no sign of oil in my coolant.

 

I figured the oil pressure would be greater than the pressure of the coolant system, hence I should see oil in the coolant. Instead, I've only observed coolant in the oil, and seemingly more evidence of coolant in cylinder 7 than the others. 

 

What do you think?

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If you look at the oil system for the exchanger, you will see that there are spring loaded bypass valves for the exchanger.  These systems were designed around 50 weight oil in the summer and 30 weight in the winter.  Most likely your car has  been in a bypass mode so no oil was forced into the coolant side.  

As for #7 cylinder, I would expect to find a crack between the valve seats on that cylinder.  

 

If you do any machine work on the cylinder head, I always recommend that you square up the bottom of the hex on the headbolts.  Then add hardened washers on the bolts.  Many times you can see where the headbolts have worn a taper into the cylinder head and sometimes have cracked the heads at the bolt holes.  I can send some photos if you need a clearer picture of this problem.

 

Bob Engle

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Good deal. I'll have the machine shop do a thorough inspection of the head when I take it in this week. 

 

Please check my first post in this thread for pictures of the head bolts holes; is that what you're describing?

 

Other than authenticity, is there a problem swapping the head bolts with all new ones? The previous owner already replaced one of the two head studs with a new bolt. Is it a common thing to replace both studs with bolts, at the risk of making head alignment slightly more challenging?

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  • 2 weeks later...

The machine shop found cracks between the bolt holes and the water jacket—seems like that's the same as your block, Bob. 

 

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They installed brass sleeves in the bolt holes. I'm not sure that will do much more than the silicone on the bolts I found while disassembling, but so it goes.

 

They also drilled and sleeved the valve guides, and took off 0.010" or so from the head surface to get it flat again.

 

Then they repainted my head silver—and didn't do a very good job of it. Now I need to figure out what paint was used before. I suspect it could've been Austin Healey Green from POR-15, though I have no way of knowing for sure. It's pretty dark, from best I can tell.

 

Before:

 

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After:

 

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My head bolts are showing some corrosion, and one has already been replaced.

 

Where can I find a set of new bolts, and hardened washers while I'm at it? Is there another engine that uses the same 5.5" 7/16"-14 bolts so I can just ask the parts guy at O'Reilly's for a set? I'm not having much luck sourcing them online... McMaster sells them, but they're zinc plated in grade 5.

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I guess finding the tall headed bolts is best left for custom machining or finding used ones? Bolt Depot has the correct size bolts in grade 5, zinc-plated.

 

Am I being overly picky for wanting black oxide instead of zinc? Or should I just slap in 20 or so grade 5 zinc-plated bolts with some washers and call it good enough? When I rebuilt my old Fiat 124 Spider, I was able to find a new bolt set. Trickier the older you go, finding a new, complete set!

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If you have access to a bead blaster, Take the zinc bolts,tape the round and threaded portion and bead blast the zinc off and then treat them with tool black to have the black oxide appearance.  

 

I can look through my bolt pile and see if I have enough for your needs.  they would be used and I could turn the shoulder square on them. At these torque levels, there is not a lot of stress on the bolts.

 

Bob Engle

 

 

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  • 4 weeks later...

A note for others reading this in the future.  A compression test before you start tearing the engine down can provide important data.  
 

A good engine shop can do a leak down test of each cylinder and the water jacket too. 

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28 minutes ago, Brian_Heil said:

A note for others reading this in the future.  A compression test before you start tearing the engine down can provide important data.  
 

A good engine shop can do a leak down test of each cylinder and the water jacket too. 

Yep! Wish I had done that instead of being overly confident in a blown head gasket! Live and learn.

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Freeze plugs are a misnomer.  I have never seen a freeze plug push out when an engine freezes.  They are actually core plugs.  Their purpose was to have a place to remove the sand casting core for the internal water passages.  On the early straight 8's, there is the side water jacket cover that allowed removal of the casting sand.  There was no need for additional openings to remove the sand.

 

Bob Engle

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Good point, Bob. So given the amount of coolant I've found in the oil, and given a little oil in the coolant...I still haven't found what I'd consider a smoking gun. There was a pinhole leak in the oil heat exchanger, and it's not clear to me that the cracks in the head were sufficient to dump such a large quantity of coolant into the oil. I suppose I'll reassemble it and try to lightly pressure test the coolant side to see what happens, unless anyone has other suggestions or places to look. 

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Dropped the oil pan to look at the strainer and give it a look from the underside. I haven't pulled the strainer yet to see what exactly it's caught.

 

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I also noticed someone used some globs of silicone on the cork gasket near the rear main bearing. How would this have looked leaving the factory? It seems as though someone thought the cork wouldn't provide an adequate seal here—maybe from experience?

 

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The vertical sides of the rear main main bearing cap has a tapered wedge seal on both sides.  a new seal in this application should be proud so the pan will compress and seal this corner.  Your photo seems to show that this seal is worn away and some one attempted to use silicone to get a seal.

 

Bob Engle

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15 hours ago, drovak said:

I also noticed someone used some globs of silicone on the cork gasket near the rear main bearing.

 Certainly not original, but not uncommon for a contemporary repair.  The dabs of silicone appear to have been applied at the seams in the pan rail where the rear bearing cap meets the block.  I think it was just insurance against a leak where the cap sits slightly below the pan rail.  Permatex #2 could also be used for a less obvious repair. 

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Where can I get this tapered wedge seal? I don't recall getting such a thing from Olson's, but then again, I wasn't thinking of needing to replace seals all of the way down there!

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I'm old school on sealants.  I prefer Permatex to the silicone stuff.  The permatex will lay down in a very thin uniform film.  The silicon wants to push out into a wad like you see in the above photos.

 

Bob Engle

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Actually you should not use silicone products around modern engines as it can and will contaminate the Oxygen sensor(s) in the exhaust.  Silicone is also not permitted in areas where paint is to be applied in automotive facilities either

Edited by Brian_Heil (see edit history)
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I don't mind using a sealant if that's what it needs, but I am certainly more inclined to do what would be more in line with what they would've done at the factory—as long as that means not leaking oil everywhere!

 

I feel like I'm undoing 35 years of small kluges here and there on this car. But at the end of the day, I want the car back together so I can enjoy driving it! :)

 

Unsurprisingly, the manuals I have for this car don't go into near this kind of detail with respect to seals and other assemblies, so I am hoping a kind soul who has been through their early straight 8 can help! :) 

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If you don't want the gasket to leak, and you want to stay "old school", use Permatex #2.  Holding the paper or cork gasket between your left thumb and fore finger, put some on both sides of the gasket and smooth it out with your thumb and finger.  Go around the gasket creating a thin coat on each side.  If the gasket is to intersect with another gasket, put a small bead on the end of the gasket that is intersecting.  I have never had good luck with straight gaskets.  That little bit of sealant on the surfaces and where gaskets intersect  makes all the difference.   

For a head gasket, I always put 2 coats of Permatex copper spray on each side.  I let that dry before assembly.    

Hugh   

Edited by Hubert_25-25 (see edit history)
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Since the main topic of this thread has to do with coolant leakage I'm watching with great interest.  I'm close to being done with restoration of my 1931 8-66S coupe but while laying under it the other day I noticed a very small puddle of green antifreeze under the rear of the engine.  I haven't made a big effort to find it yet but oddly it is dripping from the vent hold on the bottom of the cast iron flywheel cover.  There is a piece of sheet metal that covers the front face of the iron flywheel cover and I can see green antifreeze tracking along the top edge of the cover.  Any input on where the antifreeze might be coming from would be much appreciated.

 

Dave...

 

UPDATE:   Rather than posting again I decided to update this one since my coolant leak turns out not to be much of a problem.  Turns out my big coolant leak is coming from the lower right corner bolt of the water jacket cover.  The cover bolts screw into open holes in the head gasket so if the copper washer and cover gasket associated with any of the water jacket cover does not seal there will be a leak.  As I stated I'm closing in on having this car done enough to put it on the road this summer.  Pulling the head to repair a leak or tearing out the oil temperature regulator would be a big tear up at this stage of the game.   This engine has been good to me, it is not leaking coolant into the oil and it runs pretty good.  I will happily take care of this minor issue.

 

 

WJC leak 001.jpg

 

WJC leak 003.jpg

Edited by Str8-8-Dave
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