350 mag mpi fresh rebuild dumping antifreeze into oil pan

gherkin

Hi all. I just finished a rebuild on a 350 mag mpi out of my 2000 270. Block was cracked so found a machine shop that had extra 880 blocks. I took them everything to check out and got the new block back bored 30 over. Had them check intake and all the manifolds and risers and they said all looked good. While out I also installed a freshwater cooling system a mfh-5320. Just put engine back in boat and began filling the heat exchanger. It took over 3 gallons of antifreeze which I thought was odd. I then ran out. So I figured I had enough in to try to turn the engine over. Before I did I checked the oil again and the oil was all of a sudden way high. So I sucked some out and sure enough all that antifreeze went straight into the oil pan. Any idea how this could be happening? Either I or the machine shop missed something dramatic for all that antifreeze to flow right into the oil pan in literally a few minutes. I’m not sure where to start to try to track this down so any advice would be greatly appreciated. Thanks.

Michael T

I'd look at head gasket, risers, oil cooler? if you let it sit for a while I think (if memory serves) the AF will rise to the top and can be siphoned out then the oil/filter changed. Good luck a PITA. Is there a warranty? 

gherkin

I did the rebuild myself.  So unless it’s a problem with the block from the machinist it’s all on me.  Head gaskets are new felpro premiums and even if it had a head gasket problem it wouldn’t leak this quickly. Risers have the new block off gasket installed.  Is no external oil cooler on this engine.  I already pumped out the entire block and pulled all the spark plugs.  No moisture on the plugs.   Just to be sure I sprayed some penetrating spray in the cylinders. On the bright side I have not turned the engine over at all so that is probably a good thing.   I’m leaning toward the intake manifold either a major crack that wasn’t there before or the new gasket didn’t seal well but if gasket it would have to be really bad to leak this fast.   But any way I can tell before tearing stuff apart?  Anybody have any clever ways that I might be able to get even a clue as to where the leak is?   Any thoughts are appreciated.  

212rowboat

i had typed out a response and then stopped... it's the speed that makes me wonder.  that happened quickly- almost too quickly for anything BUT a cracked intake... EVEN if it was an internally cracked exhaust manifold a cylinder would have to have leaked down really quickly, which is possible and certainly would do just that- but that quickly? 

so... unorthodox to say the least... but... 

pull the blue plug on the circulation pump and blow some air in there- you'll want the compressor some distance away or using bottled air.. use ye' ol' mechanic's stethoscope- which in my condition is a long handled screwdriver.... use your ear and the stethoscope to see if you can determine where the leak is... if it's enough to pass that much coolant, then it's gotta be big enough to be heard?   

i'd like to hold the risers suspect, but that only leads back down to the heads... and even if the valve was wide open there would it defeat the rings as quickly as you describe and flood the pan? ... just doesn't seem right... 

other than all that- a cracked block could do it.. but that fast? 

i'm all ears, man (no pun intended)... it's baffling other than a cracked intake manifold... 

Aqua_Aura

This is probably a stretch and I'm not looking at a diagram but since this happened so quickly and you installed a freshwater cooling system is it possible to cross a cooling line with an oil line? 

Did you fill the oil fill instead of the antifreeze. It seems silly but it's possible. 🤷🏽‍♂️

reneechris14

If leaked down that fast I would put air to the cap and listen for air. I would also say intake,  there is no other way to it could to the oil pan that easy.

gherkin

Thanks for all your thoughts.  I’m going to do some more diagnosis and report back.  I’m also leaning toward intake.  I’m thinking. If I remove the distributor and put one of those inspection cameras down while someone is filling it I should be able to physically see an intake leak.  Correct?   If it ever stops raining I will get back to work on it. 

212rowboat

If you're going to scope it, I'd wager pulling the valve covers and #1 or #2 rocker and push rod out and going in from there would give you a better look. 

212rowboat

And instead of coolant or water, I'd get a jug of WD40 for that purpose... on the off chance it will disperse and chase pooled water/coolant to the pan. 

69fastback

I’ve never worked on a closed cooking system boat. Can you use an automotive coolant system pressure tester on it? They’re free to rent from any auto parts store.  

212rowboat

69fastback said:

I’ve never worked on a closed cooking system boat. Can you use an automotive coolant system pressure tester on it? They’re free to rent from any auto parts store.  

Yeah, it can be done.  I did it with my air lift after assembly to prove all the gaskets and hoses were sealed.... took ot to 20 inches of vacuum, complete with hoses collapsing and let it set a while.   Its the same thing but in opposite (pressurizing instead of drawing vacuum) i was suggesting, and using a stethoscope to locate the leak without having to disassemble anything.  

This is a strange situation to be sure. The only thing that holds (or doesn't hold) water is the cracked intake manifold... but even a crack won't leak that fast.... this is a strange one. 

J3ff

If it was flowing into the exhaust would it be able to get to the oil pan? ie. he used the wrong gasket between the manifold and the riser? 

212rowboat

I once heard.... no, I've heard a million times "a cracked manifold leaks into the cylinder; a failed gasket leaks into the crankcase."... specifically about vortecs, they use a specific type of gasket OE, and that gasket can't be overtorqued or it breaks...its freakin plastic and rubber... it also uses bolts that bottom out purposely and so the gasket won't be damaged- and OE relies on bolts with locking dressing on the threads... all because of that gasket, and the gasket because of the angle..... grrrr... but when they're right? They're awesome.... 

You CAN get an aftermarket gasket now that is impregnated metal.... theyre a little thicker, amd once you get to proper tq they wont be bottomed out... you can use the OE bolts (but dont reuse them) TTY bolts, or straight up grade 8 so long as you mind your tq values.  

Prediction: you're going to find a mangled intake manifold gasket... you were pouring into the exchange which went to neck and into manifold and straight into valley then crankcase... 

Not a lot of folks know about the issues with vortec intake manifold gaskets.... theyre a problem.  There is a solution, now, but they were a problem for a while.  If you grabbed the wrong kind which don't have the little lips that extend into the water jacket on both sides of the port, you'll have this.... if you over torque you'll have this.  If you reused bolts you'll have this... if you used bolts without locking dressing (other than NEW OE bolts and with the OE gasket) youll have this. If you used bolts a thread too long youll have this. 

I saw a post on FB where a guy was having issues losing coolant and I remembered that little adage "cracked manifold floods cylinders; bad gasket floods crankcase"... i should have remembered that immediately.  

69fastback

212rowboat said:

69fastback said:

I’ve never worked on a closed cooking system boat. Can you use an automotive coolant system pressure tester on it? They’re free to rent from any auto parts store.  

Yeah, it can be done.  I did it with my air lift after assembly to prove all the gaskets and hoses were sealed.... took ot to 20 inches of vacuum, complete with hoses collapsing and let it set a while.   Its the same thing but in opposite (pressurizing instead of drawing vacuum) i was suggesting, and using a stethoscope to locate the leak without having to disassemble anything.  

This is a strange situation to be sure. The only thing that holds (or doesn't hold) water is the cracked intake manifold... but even a crack won't leak that fast.... this is a strange one. 

Well, that would reveal where the coolant went and it’s easy. 

gherkin

Can anyone see my attachments?  So what I seem to be seeing is that every corner of my head gaskets are leaking, or at least it looks like that is where it is coming from.  See the one pic with water flowing, and then the next one once it is done.  It can't possibly be coming from between the head gasket and the block can it?  It looks that way or is it just running down.  I used the good felpro head gasket and intake gasket, the intake is the one that is metal and rubber and yes there were pins so it fit in place perfectly and used the black tube that came with it to do the ends. 

gherkin

Also, as I was reading previous posts, I did torque the intake manifold bolts to specs which was not much something like 12 foot pounds? I can't remember, but it was light.  I did not use new bolts.  and I also did it in the proper torque sequence.  I am quite certain that the gasket is in place properly.  just for fun, should I crank them down a bit more and add more water to see if it slows down? 

Michael T

........@gherkin, so sorry for your troubles. PLS be careful when torquing your intake manifolds down more. respectfully I'd be careful and set my torque wrench to merc. specs. and re-torque in sequence (as you did the first time) and see what happens. When you try to re-torque do the bolts tighten more?

gherkin

So I took the intake manifold off and to my surprise I am not seeing any issue with it.  So I started filling a hose with water and sure enough the leak appears between the head and block almost like it’s coming out where the gasket is.  Happening on all 4 corners even when just pouring water down the head ports.  Has to be cracked heads now wouldn’t you think?  From talking to the machine shop the other day sounds like they didn’t pressure test them.  Isn’t that a normal part of the process to pressure test the heads?  Just getting disgusted here.  If I would have known all this I would have just got a new long block.  Any thoughts / recommendations at this point.  

212rowboat

dang, man... has GOT to be frustrating... 

Clearwater has good heads at good prices dressed how you need them... I'd give them a shout.  

I'm sorry you're going through this. 

dalek

Head bolts too long maybe? Either previously stretched or the block was skimmed. If the head is coming off anyway, check they are not bottoming out.

Black_Diamond

To leak that much, it is not a crack, or it would be obvious. A poor machine job decking the block or when refacing the heads sounds more likely. 

gherkin

So turns out I ordered the wrong gaskets.  They were so close I even looked them over real close prior to installation.  But there was a spot on all 4 corners that allowed the water to just run right down but couldn’t see it with the scope.  So just a stupid mistake on my end.  Thanks everyone for your help.  Got new ones on order so hopefully I get it right this time.   Thanks again. 

Handymans342

Let us know it’s running. 

gherkin

Yes thanks Al. I fought that battle when I put them on the first time.  Didn’t realize these had TTY bolts and was trying to torque them normally and they kept stretching.  It’s been a long time since I’ve rebuilt an engine and I had never even heard of TTY.  So I just bought good ARP head bolts and plan to torque them to 70 lbs per their directions.  

gherkin

Yes I’ve got the good marine head and intake gaskets from Fel Pro.  Now I have installed a full fresh water cooling system.  So technically I could have probably gone with automotive gaskets since it will be antifreeze running through the engine and manifold. But if figured I had put this much money in it no sense cheaping out on gaskets.  You feel like I would have been better off with the TTY head bolts over the ARP ones?   I just finished putting it together for the second time tonight.  Let me know your thoughts.