3FE Head Gasket

[Rush]

Have you checked the oil cooler?

I have, and I haven't...
I bypassed it with straight hose and the cooling system still lost a bit of pressure, although I didn't test it before bypassing.

I could try to pressurize just the oil cooler, but it'll take some doing.
Is it that common that they leak? I didn't have _any_ oil in the coolant.

 

[Rush]

92 3FE Internal Coolant Leak seems oddly familiar, in terms of symptoms.

A few other similar posts here on MUD seem to be cracked heads.

How hard are 3FE heads to come by, these days?

 

[Rush]

Have you checked the oil cooler?

I did today.

I pushed a female air chuck into the upper coolant hose on the oil cooler and clamped it down:

I did the same thing with a 3/8" extension on the lower hose:

And the bastard held pressure.

So it's not the oil cooler.

Damn.

 

[Rush]

I'm almost done figuring out how to seal the head to confirm that's (not) it.
I'll post this weekend with results.

 

[Rush]

So I've had a bit of a time with this part.
For some reason I've tried really hard to keep this as universally DIY as possible, even when I'm sure I could have found a sheet of rubber on Amazon that would seal perfectly and quickly. And I may need to.

After prepping the area around each coolant passage with brake cleaner, I put a single piece of Home Depot window sealing tape (for winterizing a house) over each hole.
Yes I know I missed one as of the photo, rest assured I sealed it as well.

Clearly that's not going to hold the pressure on its own, so I needed a backing material that was firm but would also give a bit.
Ghetto as it may look, I then put sheets of cork over the holes, to press/seal the tape against the head.

The Mrs. had them laying around for a project of hers, but I figured at $5 a pack at walmart, it was worth a shot.

Side profile of a 4-pack of the sheets:

I didn't even use a full sheet.

And here we are, on an MDF sheet for flatness and rigidity.

I'll get the coolant system pressure test kit (and adapter set) from the local oreillys a bit later, as well as a few more C clamps, and see what I can't find out about this head today.

 

[Rush]

So the ghetto head test rig happened.

To seal the thermostat housing, I plugged the two hoses on the lower housing with 3/8" drive hex bits and capped off the two little pipes with heater hose. One of the hex bits in the photos wasn't airtight, so I swapped it out for a 12mm 1/4"hex-drive socket that was.

Interfacing the coolant pressure tester with a bare tstat housing was always going to be interesting, but I found a way.

The piece you see above is the radiator cap tester adapter, sealed against the tstat housing with a big flat o-ring from the additional adapter set.
The ziptie harness, while slightly fiddly to implement, has help up perfectly.

I pumped the thing up, worrying the whole time that every one of the seventeen pieces of tape+corkboard was as bad an idea as they sounded when explained to anyone older than 5, and I waited.

And it didn't hold pressure. I mean, it didn't just never build pressure, but it leaked somewhere.

So I got a few feet of 3/8" plastic hose and held one end to my ear, the other probing for hisses.
After threatening my 13yo with bodily harm more times than I thought it should take to get him quiet, I was able to listen EVERYWHERE on the damned head for leaks.

No hissing, but it was losing pressure somewhere.

So I checked the tstat housing a second time, and fiiiiiinally found a sound.
Not hissing, not whistling, just... blowing.

I handed the hose first to my kid, and then to my brother. They almost didn't notice it either, until the fly buzzing around the garage took a break and it was actually silent.

In the presence of soapy water, a constant stream of bubbles formed around one of the housing bolts.

Even after retorquing the bolt, I still got bubbles. So it's the gasket, then.

Knowing the PO had mentioned the thermostat, and since I have a new Toyota one to put in anyway, I popped open the housing.

It wasn't a Toyota. And it didn't have a rubber O-ring.

And it wasn't a 190 degree tstat, either. (Original tstat -I assume- that was in a box in the truck when I bought it, for comparison.)

Someone's been fighting thermal gremlins in this motor.
Joy.

Oh well, at least this is correct:

And yes, the original water/coolant temp sensor had snapped off like I've read about here on MUD in other threads. This one is new, Toyota brand.

 

[Rush]

It's not the head's coolant passages.
I took it to 16 PSI, and the only bubbles were coming out of the tstat housing's bolts, new paper (and RTV) gasket, or its hoses with erstwhile plugs:

Everywhere else was quiet:

That's a relief.

 

[Rush]

The valves, on the other hand, were, uh, less airtight.
I followed this method of testing:



Both valves in cyl2 let bubbles through, which you can see in the exhaust port:

and cylinder 5's exhaust valve even leaked water through:

I'll need to get the valves out and have a look, I suppose.

 

[Rush]

So the exhaust valves look beat to death, but the intakes are alright.

The exhaust seats should have a nice, soft radius, right? Not a nasty, crisp, free-flowing angle like the intakes...

Does anyone know about rehabilitating these on the 3FE?
Can they be recut/reground, and are those exhaust valves salvageable?

 

[fjbj40]

Before thinking about a regrind you want to measure for stretch. If there is any then no, they are not worth doing. measure the diameter of the stem to check for stretch. They are not worn to badly and can probably clean up easily. Back cutting would also help the flow a little also, but this is a tractor engine remember .
I would regrind all of it if it were me. But I have the tooling to do it also. Just drop it off at a reputable engine machine shop and get it all refreshed, you have come this far, might as well do it correctly!

 

[Rush]

Before thinking about a regrind you want to measure for stretch. If there is any then no, they are not worth doing. measure the diameter of the stem to check for stretch. They are not worn to badly and can probably clean up easily. Back cutting would also help the flow a little also, but this is a tractor engine remember .
I would regrind all of it if it were me. But I have the tooling to do it also. Just drop it off at a reputable engine machine shop and get it all refreshed, you have come this far, might as well do it correctly!

You mean I can't just do this myself (Projects - DIY valve seat cutting) and have it work perfectly?

Seriously though, thank you for the encouragement.
And yes, this is a longevity/never-have-to-fix-it-again build, not a baja 500 motor.

I'm thinking that going with SBC exhaust valves is the most direct route to getting it running again. There's a good shop nearby that should be able to navigate the details of it.

Speaking of which, after some searching in the forum I have the following as the details on the usage of SBC valves:
Exhaust: Cheapo stainless 1.5" SBC valves. Get the "+.100" variety so I can keep my 3FE rocker assembly.
Intake: Cheapo stainless 1.84" SBC valves.
Seals: Have the machinist size the OD of the valve guides down to 11/32" so it'll accept a Ford inline-six valve stem seal of that size.
Seats: Cutting/grinding them to fit the larger valves is all the reconditioning they need, and obviates the otherwise-necessary step of pulling/pressing in new ones which would also need cutting/grinding anyway.
Guides: Due to the larger diameter of the SBC valves' stems the originals can just be reamed to fit, thus avoiding replacement.

Am I missing any details?

 

[Rush]

Just noticed this in the 3F manual:

NOTE: The thermostat on the 3F engine is equipped with a by-pass valve. Therefore, if the engine tends to overheat, removal of the thermostat would have an adverse effect, causing a lowering in cooling efficiency.

Anybody have any info on this bypass valve?

 

[Rush]

So, I just noticed something.
3FE Head Gasket

and
3FE Head Gasket

It looks to me like the PO didn't put alignment dowels back on the motor when he did the head gasket.
Both the 3F and 3FE FSMs mention lifting the head straight up off of the dowel pins, so I'm assuming this motor had them originally.

@FJ40Jim mentioned it in this 2F thread(How NOT to restore the FJ40). That's enough proof for me, the 3FE needs them too.

Anybody know what specs/part numbers the dowels/sleeves/pins are?

 

[Rush]

Regarding the dowels, I ordered the 2F ones in, and I'll see if they fit.

As far as testing the block goes, I finally rigged something up.

I taped off the coolant passages with the same window sealing tape as I used on the head, backed with the same cork sheets.
The head was handy, and makes a good weight. Real good.
The rachet straps worked well but bound on the sharp edges of the head, so I put a few impact sockets underneath to help the straps move while tightening.

I sealed off the pump with a section of 5/8" heater hose, and plugged the other end of the oil cooler heater hose. I pressurized the system with the same oreillys radiator/cap pressure tester as before, which I hoseclamped to the end of the lower radiator hose.

It lost pressure steadily, so I got out the soapy water.

I found the leak to be at both ends of the upper segment of the lower radiator hose (pump-to-pipe):

The water pump _itself_ is also leaking, which of course gives me warm, happy feelings.

But it's still preferable to having eliminated all leaks but the block!

 

[TomOsborne]

This is great. I have looked far and wide for pics, especially on the vac. Watching. Great future reference.

 

[TomOsborne]

...and this whole thread is awesome.

 

[Rush]

...and this whole thread is awesome.

Thanks, man.
The forum has soooo much knowledge here, I figure I can totally give back by taking photos and documenting what I find along the way.
I won't be the only one that'll need to remember where everything goes, etc.

 

[Rush]

Quick update on head gasket alignment without the dowels.
I pressed the old gasket against the head so that the indentations matched against the coolant passages, and this is what I found:

Probably not catastrophic, but worse than I feel comfortable with.

Can't wait to get the dowels from the dealer.

 

[Rush]

Also, my kid loves the cruiser:

 

[Rush]

Dropped the head at Clegg Machine in Orem for a valve job.
They're oldschool machinists and I've heard nothing but good about their work.