Do I have a blown head gasket

[georgeg305]

My thoughts:
On my M-25, ( three cylinder ) Do the following to check the engine. When the engine is running, Take off the "radiator" cap. If you see a tiny bit of oil and bubbles, you likely have a blown head gasket, it is also likely that you have warped the head. Take it to a machinist and check that the head surface is true when you replace the gasket. Note that there is a specified order/procedure when tightening the head bolts


As a general overall engine check, with the engine at idle rpm, crack open the "B" nut on one of the injector feed lines. You should get one of three results.
1. A slight sag in engine rpm. You may not even see it on the rpm but you can definitely hear it: Normal operation. The engine is now running on 2 instead of three cylinders
2. Nothing happens: The engine is already running on just two cylinders and you are fooling with the cylinder that is already dead.
3. A major drop in rpm. You may have to add throttle to keep it running. The engine was already running on just two cylinders and you just killed one of the good ones.
You can confirm your findings by doing the process on a different cylinder.


This process works because, at least on the M-25, you may not be able to tell whether the engine is running on two or three cylinders without a comparison. My normal engine will produce 800-1000 rpm with all three cylinders working. Two cylinders will produce just a few rpm less.

[skipmac]

Well, after reading all the info, ideas and suggestions I think I may have a solution to what's going on.

From all comments it's very unlikely for the fresh water system to be leaking into the cylinders - pressure differential and the volume of water that is lost.

Same for leaking into the oil - no or limited path between water and oil passages, the large volume of water lost AND the oil is clean and clear.

Also, I am not seeing any steam, leaks or drips anywhere in, on or around the engine, hoses, pumps, coolers, etc.

AND I just started thinking, the water in the fresh water tank is brown. Now without antifreeze the water inside an engine cooling system can easily be brown and dirty BUT as much water as I've been replacing I would think it wouldn't be that brown.

AND where else can the water go and where can that volume of water go? The heat exchanger which is also pumping brown river water through the system.

Adding all the bits of info I'm thinking (hoping) I panicked and jumped to the worst case scenario and it is just the heat exchanger. Going out Monday and pulling that puppy off to have a look.......... unless someone comes up with a different, more likely scenario.

[jkishel]

From your description, fresh water (coolant) is being lost to the exhaust. That can happen either because the heat exchanger is leaking (coolant is at higher pressure than raw water), or there is a leak (crack) between the coolant tank and the exhaust manifold (coolant is at higher pressure than exhaust gas). To determine which is happening, could be both, you need to use a pressure tester as mentioned.

First, remove the radiator cap and pressure test the coolant system. Pump it up to 10 or 15 psi or so and see if the pressure holds for many minutes. If the pressure drops, you have a leak. If you can’t see any external leaks, Remove the raw water hose from the heat exchanger discharge and repeat the test. If you see coolant dripping from the heat exchanger discharge, the heat exchanger is leaking and should be repaired or replaced. If you don’t see any coolant dripping, the water is leaking through a crack from the coolant tank into the exhaust manifold. Remove the tank/exhaust manifold to inspect.

[Titti4]

I once had cracks in the valve seats so that compression leaked into the cooling channels. Had to remove the head and had the cracks welded and the valve seats recutt...

[skipmac]

Originally Posted by jkishel

From your description, fresh water (coolant) is being lost to the exhaust. That can happen either because the heat exchanger is leaking (coolant is at higher pressure than raw water), or there is a leak (crack) between the coolant tank and the exhaust manifold (coolant is at higher pressure than exhaust gas). To determine which is happening, could be both, you need to use a pressure tester as mentioned.

First, remove the radiator cap and pressure test the coolant system. Pump it up to 10 or 15 psi or so and see if the pressure holds for many minutes. If the pressure drops, you have a leak. If you can’t see any external leaks, Remove the raw water hose from the heat exchanger discharge and repeat the test. If you see coolant dripping from the heat exchanger discharge, the heat exchanger is leaking and should be repaired or replaced. If you don’t see any coolant dripping, the water is leaking through a crack from the coolant tank into the exhaust manifold. Remove the tank/exhaust manifold to inspect.

Thanks. Good step by step test procedure for the cooling system.

I'm hoping it's in the heat exchanger. Since I had to replace the oil and transmission coolers a couple of years ago and didn't do the heat exchanger at the same time I think that is a likely source of the leak.

[skipmac]

Originally Posted by georgeg305

My thoughts:
On my M-25, ( three cylinder ) Do the following to check the engine. When the engine is running, Take off the "radiator" cap. If you see a tiny bit of oil and bubbles, you likely have a blown head gasket, it is also likely that you have warped the head. Take it to a machinist and check that the head surface is true when you replace the gasket. Note that there is a specified order/procedure when tightening the head bolts


As a general overall engine check, with the engine at idle rpm, crack open the "B" nut on one of the injector feed lines. You should get one of three results.
1. A slight sag in engine rpm. You may not even see it on the rpm but you can definitely hear it: Normal operation. The engine is now running on 2 instead of three cylinders
2. Nothing happens: The engine is already running on just two cylinders and you are fooling with the cylinder that is already dead.
3. A major drop in rpm. You may have to add throttle to keep it running. The engine was already running on just two cylinders and you just killed one of the good ones.
You can confirm your findings by doing the process on a different cylinder.


This process works because, at least on the M-25, you may not be able to tell whether the engine is running on two or three cylinders without a comparison. My normal engine will produce 800-1000 rpm with all three cylinders working. Two cylinders will produce just a few rpm less.

Excellent trouble shooting technique and helpful to diagnose a couple of problems. I've done this before but it's been several years and good to get a reminder so I keep it in my trouble shooting tool box.

[hellosailor]

skip-
There are two very simple old dye checks that can start you out. The first is a dye that goes into the coolant. If there are any combustion gasses being pushed into the coolant, the dye typically turns blue so there's no problem spotting bubbles, the whole thing turns color. Any real auto parts shop should carry it, if not ask a local radiator shop.
The second is to add a UV dye, basically fluorescien. Then you run the system for ten minutes, turn out all the lights, and put on the yellow googles that came with the leak test kit (same kit that is used with AV systems, just a water-based dye instead of oil based) and run a blacklight over the system. If there are any leaks or weeps, they'll light up brightly under the black light. Let it run for a while, keep checking. If nothing turns up, by all means hold a clean white (not washed in UV-enhanced "whiteners" detergents) towel or rag over the exhaust for a minute, and then look at THAT under the black light. If you see the green glow in the rag--you're blowing coolant out the exhaust and have a head gasket leak.
Usually the cheapest way to go is to buy a $50 black light kit for AC systems, has a bright light and the goggles (which are more effective than you'd think) and for another two bucks get the radiator dye to use with it.

A head gasket, fwiw, is just wrenching. Yes, you will need a torque wrench if you don't already have one. They're incredibly cheap these days. And yes, there's usually stuff in the way...intake or exhaust mainfolds, wire harnesses, STUFF. But you're basically unbolting a heavy casting, checking the block with a straightedge for warping, looking for cracks, looking for any signs the gasket might have simply blown out. If everything looks OK, then you check the head itself, and usually drop that at a machine shop if there's any question that it has warped or is not perfectly flat any more.
Clean surfaces, buy good new gasket kit, bolt it back up. Use new head bolts if the instructions call for that, some deform after one installation and must be tossed. Just careful wrenching that will consume two days (one on, one off) for most folks. And, you come back in a month to re-torque all the head bolts afterwards. That's really important.

But first do the dye checks, they're fairly quick and painless.

[jmschmidt]

Do a detailed inspection of the joint between the head and the block. If the heat gasket is blown this will be pretty easy to detect. Start the engine from stone cold with coolant cap off. Look for bubbles in the coolant or maybe even a geyser. This indicates a possible blow gasket into the water jacket at some point. Pull the dipstick and check for water droplets or, as mentioned, drain a little oil to check for discoloration or maybe even water separated from the oil.

[Siberian Sea]

Here is how you check....
First top off coolant. Then take the small hose that vents your expansion tank. It’s the small hose that is connected to the expansion or what would be known as a radiator cap. Place the open end of this hose in a small jar half filled with clean water. Make sure the hose is below the water level. Next start engine.
Now after the engine is hot you look at the jar of water. If you see bubbles in the jar from gases coming out of the hose you have a blown head gasket and this is the gases from the cylinder pressures going into the cooling system.
But if the water goes down because it’s being sucked into your cooling system then you probably have a cracked cylinder liner and the coolant is being burned in the engine or passing into the crank case oil and there it is steamed off from hot engine heat.
In both cases you will experience a loss of coolant. One is forces out of the expansion tank through internal pressure and the other it is sucked into the engine and consumed through combustion or contaminated lub oil. Check your engine oil to see if it appears milky or with a gray slime. This is water in the oil.

[skipmac]

Originally Posted by hellosailor

skip-
There are two very simple old dye checks that can start you out. The first is a dye that goes into the coolant. If there are any combustion gasses being pushed into the coolant, the dye typically turns blue so there's no problem spotting bubbles, the whole thing turns color. Any real auto parts shop should carry it, if not ask a local radiator shop.
The second is to add a UV dye, basically fluorescien. Then you run the system for ten minutes, turn out all the lights, and put on the yellow googles that came with the leak test kit (same kit that is used with AV systems, just a water-based dye instead of oil based) and run a blacklight over the system. If there are any leaks or weeps, they'll light up brightly under the black light. Let it run for a while, keep checking. If nothing turns up, by all means hold a clean white (not washed in UV-enhanced "whiteners" detergents) towel or rag over the exhaust for a minute, and then look at THAT under the black light. If you see the green glow in the rag--you're blowing coolant out the exhaust and have a head gasket leak.
Usually the cheapest way to go is to buy a $50 black light kit for AC systems, has a bright light and the goggles (which are more effective than you'd think) and for another two bucks get the radiator dye to use with it.

A head gasket, fwiw, is just wrenching. Yes, you will need a torque wrench if you don't already have one. They're incredibly cheap these days. And yes, there's usually stuff in the way...intake or exhaust mainfolds, wire harnesses, STUFF. But you're basically unbolting a heavy casting, checking the block with a straightedge for warping, looking for cracks, looking for any signs the gasket might have simply blown out. If everything looks OK, then you check the head itself, and usually drop that at a machine shop if there's any question that it has warped or is not perfectly flat any more.
Clean surfaces, buy good new gasket kit, bolt it back up. Use new head bolts if the instructions call for that, some deform after one installation and must be tossed. Just careful wrenching that will consume two days (one on, one off) for most folks. And, you come back in a month to re-torque all the head bolts afterwards. That's really important.

But first do the dye checks, they're fairly quick and painless.

Thanks. I assumed some kind tracer, sniffer, dye or what have you was available for this but didn't realize they were cheap and that easily available. Definitely going into my tool kit.

I'm feeling less like it's a head gasket but encouraging to hear that is a reasonably doable job if it comes to that. I kind of felt like the actual removal/replacement part was just wrench twisting but wasn't sure about any of the secret details like use or don't use special goops, never reuse this part or that, only hold the wrench in your left hand on odd numbered days or never replace the head gasket on a Friday.

[Randall M]

There is a test available at parts places to see if there is exhaust gas in radiator


Randall

[sailah]

I went through a blown head gasket on my Westerbeke 44B (Mitsubishi), took me a long time to figure it out. I replaced my head gasket a few years ago when I had a valve issue but did not check head for flatness as I had no reason to suspect it.

Fast forward to last summer and I was noticing a far amount of large bubbles going up my see thru tube from rad cap to expansion tank. Eventually I would get overheating warnings and at one point the alarm went off.

When I would check, all the coolant was being pushed up to the expansion tank, leaving only a little in block and exhaust manifold and it would get hot.

So I bought all the tools. Combustion gas analysis tester, leak down tester, compression tester and coolant system pressure tester.

The combustion gas tester is easiest to use and black/white. Mine failed within 5 seconds. It's basically a turkey baster with 2 chambers and some special fluid that turns a different color when in the presence of combustion gases. And you don't need to disassemble anything, just stick in radiator cap and run engine.

https://www.amazon.com/UView-560000-...s%2C134&sr=8-4

After I failed that I knew head was coming off anyways. But I performed a leak down test to see if I could find the source. Basically you just run compressed air into cylinders at TDC (like when you do a valve check). If you can hear the air in oil-bad rings, intake-bad intake valves, exhaust-bad exhaust valves.

In my case I had a leak between cyl 2-3 and was going into coolant jacket.

Removing the head is pretty simple, just unbolting stuff (on my Mitsubishi at least).

This time I checked the deck with a 15" precision machinist level and feeler gauges. Scraped surface super carefully. I bought expandable rubber plugs for the bores so gasket crap didn't get down there. And a neat trick I saw on Youtube was to use shaving cream in the coolant passages to keep junk from going in there.

Then I brought head to a local engine machine shop and he Dykemed the head to show me where the low spot was but I already knew it since I checked it on a granite surface plate. He cut I think 0.003" off the head and that cleaned up everything, 0.002" is the spec on mine. I also had him Magnaflux the head to check for cracks. The bill was $100 for the head surfacing and $180 for magnaflux even though he told me it was a waste of money I did it anyways.

New head gasket, torque wrench, various gaskets etc.

All fairly straight forward if you have a factory service manual.


Oh I also pressure tested my cooling system which I think you should do too. It's dead simple to use, just attach like a radiator cap and pump up. Mine held 15 PSI for 5 min so I knew my cooling system was tight.

Both the pressure tester and combustion gas tester can tell you a lot and they require zero disassembly.

https://www.amazon.com/Stant-12270-C...s%2C138&sr=8-3

[waterman46]

Originally Posted by Teknishn

Based on the above it doesn't sound like an engine problem but rather, possibly, a leak in your heat exchanger/condenser and you are losing your cooling water over the side through said leak. The harder/slower starting may or may not be related. Just my thoughts...

Yes, since no water in the oil, no steam in the exhaust or external on the engine, it is possibly a heat exchanger leak. I was able to pressure test my 4-154 heat exchanger by disconnecting either the raw water or coolant lines and using a bicycle pump and pressure gauge. Can't remember the details, sorry, but it wasn't too difficult.
One little item I made up that I find very useful is simply a threaded pipe coupling with a hole drilled into it, into which I soldered a metal tire valve. One side of the coupling is connected to a pressure gauge and the other sideconnects to the assembly to be tested. This provides a way to pressurize any section of pipe or tubing, provided one has the necessary adapters and plugs.

[bowenst7]

Check your tube stack if fitted ,mine had multiple small leaks. I thin due to using the more ecological propylene glycol based antifreeze.

[donradcliffe]

Block tester kit from Amazon--alsos available at NAPA.

https://www.amazon.com/Block-Tester-...a-570352767565

The only heat exchanger leak I found was obvious. I took out the tube stack blocked one end, and poured water into the tubes--the several tubes which didn't hold water had holes in them. The boat was in Bali, but I found an oil cooler for a fishing boat on the shelf in a Chinese store and plumbed that in.