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Old 11-02-2008, 07:19 AM
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SBC 305 cracked head, blown gasket or?

Sometimes I think I should just stick to my day job; toss away my tools and find a hobby that involves knitting or paper and paste. I need a little help (again) with a problem with my project truck.
Background: About 4 years ago I embarked on my first attempt at building a rod. I farmed out a 1935 Olds parts car to a local rod builder and had the car sliced and diced into a pickup. Installed it on a 1947 Ford truck frame with a Camaro 2.56 diff and 75 Nova front clip. I picked up a Buick Regal with a 305 SBC for the power plant and mated it to a Turbo TH350. The 305 ran nice when I brought it home; a little smoke when first fired up but otherwise fine (I now know better). I cleaned up the engine and dropped it into the truck frame. Covered it with tarps and let is sit outside while I smoothed out the body. Four years latter and after a severe back injure, job loss and minor heart attack Im back to work and have the money to work on the toy again. I wanted to toss out all the anti pollution crap on this naturally aspirated engine so I picked up a used aluminium GM intake from early 80s. Pulling off the original intake I found enough sludge to plant a tree in. Hmm guess the 305 Cam maybe toast! Pulled the Cam out and yup 2 or 3 lobes are worn down. Gee what else could be wrong? I pull off the heads; the right side looks excellent, left side not so good. Seems even though Id covered the frame and motor water had entered via the carb and pooled in the # 7 cylinder causing rust on the cylinder wall and ceasing its rings. Since the exhaust valves were a little loose I sent the heads out for exhaust valve sleeves, honed the block, changed the rings , rod bearings, installed a low end Comp Cam, new water pump and assembled the engine using a gasket kit from Felpro.. While assembling the engine I lubed up the motor well (maybe too well with oil pooling on top of the pistons. Fired up the engine. It seemed to run ok, maybe a little hot (not boiling), and shut it down after 10 minutes. Checked the oil and water; everything seemed OK. I brought my local mechanic over to see if the engine was not running too hot. He aimed a gun at my exhaust manifolds and said they were fine but suggested I change the thermostat as my lower rad hose was a little cool for his tastes. When I stalled the thermostat I noticed there was no water in the aluminium intake?? So I added coolant (antifreeze) via the thermostat opening about gallon. Buttoned the end again and went to fire her up when I was struck with an epiphany. Where did the water go the first time (water not antifreeze)? I checked the oil; ST it was a little white (not foamy but a little creamy coffee in color). Checked the water a found it looked odd. I drained the water and found it looked blackish. (Remember I added antifreeze but did not run the engine before I drained it). The right side of the block appeared to have the clearest water and antifreeze mixture. The Right side (# 7 cylinder had the pooled water rust damaged) appeared to have the most water. Both appear to have oil but the left would have more. FYI: The rad is new with no internal Trans oil cooler. After draining the coolant into a bucket the oil fell out of solution after a short period of time. 
Here are the mistakes I know Ive made: A) I pulled the engine apart before the system was pressure tested. My garage guys are some pod I did this (sorry). B) The heads were not checked for cracks when the valves were ground. C) I used the wrong gasket kit .I used a SBC 350 Felpro set. Seems a 305 has smaller pistons. I missed that part when assembling.
My biggest quandary is how did the OIL get into my Cooling System. I can understand how water can get into the motor oil but not motor oil into the rad.
Do I have a cracked head from the water possibly pooling in the head (#7 intake valve) and then freezing? (I live in up state New York; it can get darn cold here) Did I crack something because the thermostat? Did the head gaskets fail do to the bore size difference? I can see no signs of tracking. Is the used aluminium intake cracked or warped.
Help!
How can I determine what is wrong the least expensive way possible?
Thanks
Oldstruck

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Old 11-02-2008, 07:40 AM
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I don`t really know of a way for oil to get into the coolant, never seen it before in my 34 years. However, it`s common for new builds to get condensation, many times I thought my new builds had a cracked head or bad head gasket due to water build up in the valve covers.
It would have been the best idea to have had the heads magnufluxed to see if they were cracked. I would run a compression check on the engine, if it falls short on one or more cylinders you`ll know to start looking elsewhere. If all pass, I would refill the coolant and do a complete system flush to make sure all the crud is out, then I would refill the system and go from there.
It`s pretty common to find the coolant level down after firing up a new build. there are many air pockets in the system. then the engine fires off and the coolant circulating pushes the air out of the vent, then pulls in more coolant from the resivoir.
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Old 11-02-2008, 08:18 AM
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This oil in the coolant has me perplexed. I hope someone out there has had some experience and can provide a solution based upon the same thing happening thier SBC. Many years ago I had a 62 Chev with a 235 six cylinder. Pushed it too hard one day. A smoke cloud form behind me all the way home; boiled over in the lane when I stopped it. Later when I went to add coolant there was oil in the coolant. Scrapped the car the next day.
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Old 11-02-2008, 11:52 AM
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Yes I`ve too seen 3 straight 6 cylinders do this, but I`ve never seen a small block do it.
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Old 11-02-2008, 04:12 PM
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I would be looking for a crack in #7 cylinder.

Steve
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Old 11-02-2008, 04:20 PM
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Thinking about this also look for a crack in the head on the spring side. I have seen this on older V-6 Ford heads (173 ci.?) some years ago. Just a thought!

Steve
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Old 11-02-2008, 06:10 PM
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I think the block is fine as the rust was not too deep. It appeared to be caused by a slow drip from the #7 intake valve and was rather easy to hone out. I'm not so sure of the head now. Maybe the water pooled in the head and froze before it had an oppportunity to drain into the top of the cylinder. I will look closely at it.
Is there such a thing as home test that can be done?
Thanks
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