Coolant Pooling in Intake Manifold - 230 Flathead 6

[rtferguson39]

The car - 1949 Wayfarer with the 230 flathead 6 of course....

Car had been sitting for two weeks before this was found, drove normally before with no white smoke from tailpipe. Radiator slightly low, but not drinking coolant at an alarming rate. 

 

I removed the carburetor for a rebuild last night, and what do I see pooled in the intake manifold? Coolant. It looks like the coolant is originating from the runner that feeds the center two cylinders (3&4).

 

I pulled the spark plugs, all look OK (slight rich, but not steam-cleaned). All valves that I could see also show normal operating conditions. 

 

I understand that most manifold studs pass into water jackets, but am not sure about head studs. Is it likely that I somehow have coolant seeping past a stud and pooling in the intake manifold? Or maybe a cracked/misdirected water distribution tube? Or does anyone believe this could be something more severe, like a cracked block? All input is appreciated. 

 

Thank you. 

 

 

[rallyace]

Leaking past a stud/bolt is very likely what is happening although all of what you listed are possibilities. If you are going to check the manifold bolts, there are 13 bolts/studs that hold the manifolds to the block. One is partially hidden and tough to see.

[Sam Buchanan]

Are you sure it was coolant and not fuel? It is common for fuel to accumulate in the intake manifold when it boils out of the carb after shutting down a hot engine. This is why hot starts can be tricky.

[kencombs]

I just looked at a spare intake and can see no way for coolant to migrate into it.  Studs may leak, but there is no connection from those holes to the inside of the manifold. 

 

I second Sam's question  as to the possibility of fuel pooling.

[rtferguson39]

44 minutes ago, Sam Buchanan said:

Are you sure it was coolant and not fuel? It is common for fuel to accumulate in the intake manifold when it boils out of the carb after shutting down a hot engine. This is why hot starts can be tricky.

I am positive it is not fuel. No smell and most certainly green coolant. 

[Sniper]

I imagine a fairly large vacuum leak if coolant was being pulled into the intake via a leaky stud/bolt.  Unless it's a crack in a port, ain't I an optimist?

[rtferguson39]

25 minutes ago, kencombs said:

I just looked at a spare intake and can see no way for coolant to migrate into it.  Studs may leak, but there is no connection from those holes to the inside of the manifold. 

 

I second Sam's question  as to the possibility of fuel pooling.

Right. Which raises my concern even further. The only things left are head studs that may possibly leak into a cylinder, and this would only show up if the valves and piston on cylinder 3 or 4 were in a perfect orientation to allow coolant to pass into the runner after shutdown/heat soak. Or as Sniper just replied, a cracked port!  

[rtferguson39]

4 minutes ago, Sniper said:

I imagine a fairly large vacuum leak if coolant was being pulled into the intake via a leaky stud/bolt.  Unless it's a crack in a port, ain't I an optimist?

Good thought. It never ran poorly enough to suggest a large vacuum leak. Hmm. So therefore, your last sentence is my biggest fear.... cracked port. I will know more this evening when I dig a little further into it. 

[Plymouthy Adams]

there are three head bolts that enter directly into the intake manifold.  The bolt between the intakes for cyl. 1 & 2: 3 & 4 and 5 & 6.  You may wish to pull these three bolts (one at a time so not to totally disrupt your head torque) and seal the threads and watch to see if this will correct or at least slow down the leak.  I would also suggest this be done one bolt at a time and check between each bolt sealed to further define the area of concern.  The head bolt will center on the intake port to the head for the three cylinder sets.

[rtferguson39]

11 minutes ago, Plymouthy Adams said:

there are three head bolts that enter directly into the intake manifold.  The bolt between the intakes for cyl. 1 & 2: 3 & 4 and 5 & 6.  You may wish to pull these three bolts (one at a time so not to totally disrupt your head torque) and seal the threads and watch to see if this will correct or at least slow down the leak.  I would also suggest this be done one bolt at a time and check between each bolt sealed to further define the area of concern.  The head bolt will center on the intake port to the head for the three cylinder sets.

Thank you Plymouthy. Certainly worth trying before I take manifolds off. For the sake of ultimate clarity, we are talking about the three head bolts circled in red in the attached photo, correct? (not my engine, just an example picture). And to confirm, 65-67 lb-ft of torque for head bolts?

[Plymouthy Adams]

bingo....you have these identified and the torque is 65-70 on the head bolts....

[Plymouthy Adams]

the water passage from the block into the head passages are a bit away from the head bolts....and the head bolt hole is not open to the water passage in the head, it would be slim chance of a really badly damaged head gasket leaking from the coolant holes to the head bolt and secondly the head bolt hole being heavily cast as it is, would not suspect a crack here but anything is a possibility.  This is just the manner of the arrangement of bolts and passages in relationship to the intake.  Good luck, hope a bit of sealant will fix or slow it down, this will let you know if a new head gasket may be in need.  Have seen stranger things for sure.

Edited October 13, 2022 by Plymouthy Adams

[Sniper]

You know, if coolant were leaking to the extent it is pooling in the intake you'd be seeing white cloud (steam) out the tail pipe.

 

Intake air flow wants to pull liquids into the engine and for coolant to pool in the intake it would have to be under pressure to go against the direction of airflow.  That or it's happening after the engine is off but before the system cools down enough to not be under pressure, assuming you have a pressurized system.

 

Sounds logical to me, but they say logic is a great way to go wrong with confidence, lol.

[rtferguson39]

12 minutes ago, Plymouthy Adams said:

the water passage from the block into the head passages are a bit away from the head bolts....and the head bolt hole is not open to the water passage in the head, it would be slim chance of a really badly damaged head gasket leaking from the coolant holes to the head bolt and secondly the head bolt hole being heavily cast as it is, would not suspect a crack here but anything is a possibility.  This is just the manner of the arrangement of bolts and passages in relationship to the intake.  Good luck, hope a bit of sealant will fix or slow it down, this will let you know if a new head gasket may be in need.  Have seen stranger things for sure.

Understood. So we're working with an "indirect link" by sealing the head bolts. I see there is an approximate 1-1.5" gap between the cooling passage holes and the head bolt holes (just looking at pictures) , but a compromised gasket just might allow some crossover.... We'll start small with the sealant and dive deeper if need be. 

She very well might need a head gasket (not for compression reasons), and other things. It is the original engine to the car, never been pulled, with only 28k miles on it, but wasn't treated very well before me. 

[rtferguson39]

13 minutes ago, Sniper said:

You know, if coolant were leaking to the extent it is pooling in the intake you'd be seeing white cloud (steam) out the tail pipe.

 

Intake air flow wants to pull liquids into the engine and for coolant to pool in the intake it would have to be under pressure to go against the direction of airflow.  That or it's happening after the engine is off but before the system cools down enough to not be under pressure, assuming you have a pressurized system.

 

Sounds logical to me, but they say logic is a great way to go wrong with confidence, lol.

Right. For all I know, something catastrophic occurred just as I arrived home and parked it, since I've never seen steam out of the tailpipe of this car to date. 

The system is stock, non-pressurized. So either an oddly compromised heat gasket, or a crack in a port, is seeming more and more likely....

[Plymouthy Adams]

unfortunately, over time in the use of composite gasket and those that stay saturated (fully service with coolant) you can get soft material between the sealing rings of the head chamber profile.  This softening due to wet and age coupled with the least bit of cylinder pressure blowby will cause the compressed air to find an exit either to the middle bolt hole opening to the block or the head bolt opening to the intake.  It is this gradual loss of material between the pencil thin segment of the gasket that results in the ultimate blown gasket as the material can no longer support the folded metal sealing ring that the gasket material supports and eventual loss of compression as it transfers to the sister bore as a full blown gasket.  

[rtferguson39]

Well, in the time I had yesterday evening I was able to perform a dry compression test, all plugs removed, and the results came back ok. Not perfect, but ok: 

1: 105 psi

2:  95 psi

3:  84 psi

4:  95 psi

5: 112 psi

6: 110 psi

 

I checked head bolt torque. All were at 65 lb-ft, or slightly higher.  I removed (one at a time) the three head bolts that pass directly into the intake ports as Plymouthy suggested, all were dry. I did apply thread sealant for reinstall. However, the bolt between the intake port feeding 5 and 6, had an odd rust stain on the bolt and head that looked like water had run down it at one point. I'm doubtful this was the culprit for a 1/8" deep pool of coolant in the manifold. 

 

I guess the only things to do next are to pull the manifolds and head and thoroughly inspect everything I can. 

The only other thought (and question) I have here... Does anyone think it may be worth pressurizing the cooling system with a tester to a minimal amount (2-4 psi) to see if I can expose any leaks before teardown? Or will this cause more harm than good to the radiator? 

[Los_Control]

I would think you could bypass the heater core then disconnect the radiator, plug bottom hose while being creative to add air through the top hose.

 

Could be very helpful finding the problem.

Certainly seems like a head scratcher though  .... seems there was no indication of a problem before removing the carburetor.

Unless there was a issue & you thought a carburetor rebuild would fix it ..... I sure would expect to see steam from exhaust though.

[rtferguson39]

1 minute ago, Los_Control said:

I would think you could bypass the heater core then disconnect the radiator, plug bottom hose while being creative to add air through the top hose.

 

Could be very helpful finding the problem.

Certainly seems like a head scratcher though  .... seems there was no indication of a problem before removing the carburetor.

Unless there was a issue & you thought a carburetor rebuild would fix it ..... I sure would expect to see steam from exhaust though.

I like this thought. Just pressure test the block and head essentially.

 

I think the timing of this coolant issue was extremely inconvenient. The carb needed to come off due to shot accelerator pump bushing, or float issue (dumping fuel out of the base of the accelerator pump shaft). There was no indication of a coolant leak before. At all. This coolant issue likely had just begun on my last drive, or even post-shutdown. No steam from the exhaust, no clean plugs, or valves. Also no coolant in the oil. The compression test numbers may indicate early head-gasket failure around cylinders 3-4. We will have to see. Certainly the first time I've seen this issue. 

[soth122003]

You might want to remove the manifolds before you pressure test. You would be able to spot a cracked port easier. It might also be a leaky manifold stud/bolt and a bad manifold gasket.

 

Joe Lee

[Los_Control]

Since I'm not a mechanic my advice is worth what you pay for it.

I would be tempted to clean up the coolant, put the carburetor back on it and run it for some time in the driveway watching it.

Then remove the carburetor again to see if the issue has come back.

 

I can not explain the coolant in the manifold, I also can not explain why there was no symptoms such as rough running or no steam.

I have seen many things in life I can not explain .... If it only takes a few minutes to clean it up and run it again .... I would want to prove it was a problem before tearing the engine apart. ..... If nothing else you would get a better idea of how big of a leak it is if it does return?

 

Seems a crack would normally come from over heating or winter freezing. Not from normal driving.

17 minutes ago, soth122003 said:

It might also be a leaky manifold stud/bolt and a bad manifold gasket.

That would make sense if a intake port was leaking & the studs enter a water jacket .... seems with the engine running & spray some carb cleaner around the intake they might locate it?

[Sam Buchanan]

Wonder if a couple more test drives would be in order before you start taking stuff apart.

 

Oops....Los Control just beat me to it. 

Edited October 14, 2022 by Sam Buchanan

[JimT]

 What i would do is disconnect heater and radiator, intake, exhaust manifolds. Keep all studs in place. Plug all water inlets, outlets with rubber plugs, use air to test engine block for leaks. Use spray bottle to check for leaks using soapy water. Air pressure 10-20 psi to start.

[rtferguson39]

This past Saturday I spun the engine over by hand with the plugs out and was able to observe coolant coming from the 3-4 intake port and into the manifold....So I began to remove the manifolds to inspect the ports...

 

All went well until it was time to remove the two bolts for the exhaust manifold under the exhaust ports for cylinders 2-3 and 4-5. (The long bolts).They both snapped, even with loads of heat applied before attempted removal. I am currently reading (on this forum) that this is a fairly common issue. They've now been soaking in PB Blaster since Saturday and I will attempt to remove the manifolds again this evening. All 13 fasteners (less the two broken long bolts) are removed, including the hidden center lower nut. Hopefully I can make some headway tonight. 

 

[rtferguson39]

Manifolds removed as of last night. What a fun process! Upon a detailed visual inspection of the intake ports, all seems fine! Thank goodness. However, I could feel some wetness around the intake valves for cylinders 3 and 4, and it certainly smelled like coolant. I'll run a leak-down test on those two specific cylinders this evening, and based on those results, more than likely pull the head.