Shaved 2F Head Pressurizing Cooling System?? (1 Viewer)

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Jun 26, 2019
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Looking for some input about a problem my freshly installed 2F is exhibiting.

Long story short, even when just cranking, it’s pressurizing the coolant. Normally I’m able to run an engine without a rad cap to bleed the cooling system, this one geysers coolant out if the cap is off. With the cap on it sprays out of a hose as if it’s overheating.

Something isn’t right. My first question is- is there anything else on these engines that could cause this besides cracked head, bad head gasket install, cracked block?

The block didn’t have any obvious cracks and the reputable shop that pulled the engine said it had 150psi across the board.

The head gasket is new and OEM Toyota, torqued to spec in sequence.

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The head isn’t cracked, had it manafluxed when 70 thou was shaved off. The head shave is actually my main concern. I had to drill new reliefs around the head bolt holes for the alignment dowels to fit. I’m thinking either:
  1. I didn’t drill deep enough (even though I measured) and the gasket couldn’t get enough squish
  2. (More likely), It felt like a head bolt started getting tight before it was all the way down, has anyone had trouble with the length of head bolts after shaving the head? They were making contact once torqued but maybe not enough... should I throw another washer under each head bolt, retorque, and see what happens?
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Let me know if you have any input!! A compression test is probably my next step, but I’d like to try the retorque+washer first before pulling the head...
 
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I would pressurize each cylinder in turn, with 100 psi (shop air) with the radiator cap off, and see which if any (or all) result in a Vesuvius moment. Also do a compression test. It's possible your (effectively longer) head bolt were traveling into dirty threads and reached max torque before the clamped fully.

I shaved 0.020 off my FJ40 head and basically saw no compression gain. I would love to hear what your new compression numbers are when you get this all sorted out.
 
Joined
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I would pressurize each cylinder in turn, with 100 psi (shop air) with the radiator cap off, and see which if any (or all) result in a Vesuvius moment. Also do a compression test. It's possible your (effectively longer) head bolt were traveling into dirty threads and reached max torque before the clamped fully.

I shaved 0.020 off my FJ40 head and basically saw no compression gain. I would love to hear what your new compression numbers are when you get this all sorted out.

Great idea, you know, I think my compression tester has an air fitting for just that. I had chased the threads, blown the holes out etc so that shouldn’t be a problem but you never know.
I think I’ll try the air test and if the leakage is fairly consistent I’ll see if the retorque + ~70 thou washer helps.

I’d be very thrilled if I can get away without pulling the head, but at this point pulling the head again would be nothing! I’ll be out of town this weekend but will definitely update the thread as I get more info or resolve this. I bought this thing with no engine and never ran the engine stock so have nothing to compare it to, but they said the 70 thou shave adds a level of pep.
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I have had s lot of heads cut for the 2Fs. Maybe a dozen? Most of them I took them all the way to the factory limit of .100 inches. It may be that my machinist just deepened the reliefs and never bothered to mention it, but I never had an issue with that. And never had a problem with head bolts bottoming out before tightening properly either.

I'd be surprised to get that much volume of leakage from a cracked head or block. Since you have not run the engine much(?) since these components were inspected, both are pretty unlikely.

Re-check head torque. You don't mention anything about retorquing the head after start up. I always retorque an F series head after a couple of warm up cool down cycles. Loss of headbolt torque is not uncommon and I have seen them actually leaking coolant out the side of the engine before retorque.

And of course compression test it.

Mark...
 
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I have had s lot of heads cut for the 2Fs. Maybe a dozen? Most of them I took them all the way to the factory limit of .100 inches. It may be that my machinist just deepened the reliefs and never bothered to mention it, but I never had an issue with that. And never had a problem with head bolts bottoming out before tightening properly either.

I'd be surprised to get that much volume of leakage from a cracked head or block. Since you have not run the engine much(?) since these components were inspected, both are pretty unlikely.

Re-check head torque. You don't mention anything about retorquing the head after start up. I always retorque an F series head after a couple of warm up cool down cycles. Loss of headbolt torque is not uncommon and I have seen them actually leaking coolant out the side of the engine before retorque.

And of course compression test it.

Mark...

Hi Mark, I haven’t run the engine at all! Just a couple quick gurgles to life from pouring gas in the carb, not even long enough to let fuel get from the tank to the engine. But I heard the gurgling in the overflow bottle from the initial cranking too. I agree that this is an excessive amount of pressure for a crack, I’ve had plenty of vehicles with cracked or warped heads but nothing like this.

Did a simple retorque work for the engine that was seeping coolant out of the side?
 
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Hi Mark, I haven’t run the engine at all! Just a couple quick gurgles to life from pouring gas in the carb, not even long enough to let fuel get from the tank to the engine. But I heard the gurgling in the overflow bottle from the initial cranking too. I agree that this is an excessive amount of pressure for a crack, I’ve had plenty of vehicles with cracked or warped heads but nothing like this.

Did a simple retorque work for the engine that was seeping coolant out of the side?

Yep. It had not been retorqued yet and IIRC (it was years ago) the torque on almost all the headbolts was down by at least 25 ftlbs. Maybe more. Was surprising to see. Retorqued and never had a problem for at least 10 years or so until I lost track of the rig/owner.

Any problems on head installation? Any chance of a damaged gasket?

Mark...
 
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Yep. It had not been retorqued yet and IIRC (it was years ago) the torque on almost all the headbolts was down by at least 25 ftlbs. Maybe more. Was surprising to see. Retorqued and never had a problem for at least 10 years or so until I lost track of the rig/owner.

Any problems on head installation? Any chance of a damaged gasket?

Mark...

Wow, that’s crazy. Would be nice if that fixes it.
There was nothing weird about the head install, head plopped onto the alignment dowels and it looked like they had enough wiggle room. A couple head bolts went to torque rather quickly but I hit them again and they were there.

Come to think of it I did actually remove and reinstall 2 head bolts to helicoil a couple of manifold bolt holes. Didn’t touch any other bolts and retorqued them, could that be a factor? Interesting.

I’ll go blow some air into the holes and see if that tells me anything.
 
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Come to think of it I did actually remove and reinstall 2 head bolts to helicoil a couple of manifold bolt holes. Didn’t touch any other bolts and retorqued them, could that be a factor? Interesting.

I’ll go blow some air into the holes and see if that tells me anything.

I would not expect that removing and reinstalling a couple of head bolts would affect anything at all.

If you have a cooling system pressure tester (well worth getting a cheap on on amazon or something if you do no have one)... pressurize the cooling system and see if that helps find where the leak is. As large volume as you seem to have escaping, removing one spark plug at a time may clearly indicate when you hit the cylinder with the flaw.

And of course, compression test it. ;) That will probably tell you right off.

Mark...
 
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Little update- I tried the air thing, don’t think it’ll work because there’s a valve in the line retorqued all of the head bolts to 90ft lbs (with an extension if that matters), then ran it for a minute or so. Sounds great and started right up, but its still pressurizing the cooling system. Seems like it’s to a lesser degree though, as no hoses were spewing. A hose dribbled and there was bubbling in the overflow for a good amount of time after she shut off. Retorque with washers, compression test next? I’m leaving town this weekend so who knows, but a compression test would be smart... I just don’t want to know... lol
 

NeverGiveUpYota

Dare me.
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Video of her first real run and the coolant bubbling...

To me it sounds like its running really sluggish; the rockers ought to be tapping a whole lot faster. Been a awhile now since I had a running 60 at my hands so the bubbling into the reservoir I'm not sure on but... as others said, first step is to get a pressure tester from an autoparts store (you can rent) and see what it says. Thereafter you can get the idle adjusted.
 
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If the coolant isn’t burning and the oil and coolant aren’t mixing and you don’t have coolant poring out the block somewhere you likely just have air in the system. The cooling system design on these seems to be problematic for trapping air and taking a while to bleed.
 
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To me it sounds like its running really sluggish; the rockers ought to be tapping a whole lot faster. Been a awhile now since I had a running 60 at my hands so the bubbling into the reservoir I'm not sure on but... as others said, first step is to get a pressure tester from an autoparts store (you can rent) and see what it says. Thereafter you can get the idle adjusted.

Runs pretty great considering I haven’t touched the carb at al! It’s still tuned for the engine with all of its smog stuff and has been sitting for a year since the engine was pulled from the donor... And the distributor is just where I dropped it in. Pressure tester would be good. If it’s cylinders 1 and 6 I’ll know
If the coolant isn’t burning and the oil and coolant aren’t mixing and you don’t have coolant poring out the block somewhere you likely just have air in the system. The cooling system design on these seems to be problematic for trapping air and taking a while to bleed.

Theres definitely a ton of air in there, I put the engine in bone dry, heaters are bone dry, but I put 3.5 gallons in and have never seen it bubble this violently out of every possible orifice from just bleeding!
 
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Well boys, I think cylinder 6 has a problem.

Pulled the plugs, they all look good.
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Cranked numerous times with plugs out, no coolant came out of the cylinders.

Compression tested, and results were stellar! Besides cylinder 6, but it still wasn’t bad.
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While putting plugs back in, I cranked it cylinder by cylinder. Once the first few plugs were in and the cardboard was still dry, I decided to skip to cylinder 6. Voila, the Vesuvius moment.
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Maybe I didn’t drill the head alignment dowel relief deep enough at the back of the head? Or somehow screwed up some other aspect? I like those ideas a lot better than the block being cracked. I guess we’ll see when I pull the head, unless anyone has any other ideas?
 
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I think I fixed it.

No more pressure in the cooling system.

Pulled the head bolt that clamps the corner with the alignment dowel.
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It was covered in coolant.
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Put Permatex #2 on it as you do for bolts that go into water jackets.

Slipped a washer that measured about 66thou on it.

Torqued to 100ft lbs, and the problem is gone. Might do the one on the other side of the rear of the head for good meausure if this problem comes back, but for now I’m calling it a victory.
 

brian

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I shaved 0.020 off my FJ40 head and basically saw no compression gain. I would love to hear what your new compression numbers are when you get this all sorted out.

i took 30thousandths off a the 2F head in my 40 a few years ago.....i picked 30 psi up in each cyl....took me back up to 150psi.
 

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