Vinegar Flush how to

[LiquidObsession]

I'm pretty sure we've already covered this. If those manifolds are so full of lime that they're choking off the water flow (BTW, I seriously doubt this) then no flush is going to get it out. It will take days of soaking in vinegar to dissolve that much lime.

Take the manifold off. Find a suitable container and soak them in 100% vinegar for several days.

There is NO WAY to do this with them on the engine.

-Charles

Pretty sure I already covered this but my mechanic looked at all of the possibilities leading up to the risers. We hit each potential component one by one.
-raw water inlet
-strainer (replaced w/ new high quality strainer)
-transmission cooler
-impeller
-pump
He told me verbatim what you said (risers? I seriously doubt it) but by the end of the season his last comment to me was ..."we've exhausted (pardon the pun) all of our options and I can't find the cause so looking at the exhaust would be our logical next step".

[t.franscioni]

Consider a faulty temp sensor too if your exhaust turns out to be not plugged up?

[LiquidObsession]

Consider a faulty temp sensor too if your exhaust turns out to be not plugged up?

One exhaust hose burst cuz it got so hot. Steam steam steam everywhere.


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[Tom_H]

Have you tried a different impeller? It's possible the hub is slipping in the impeller (been known to happen on new ones occasionally) and that it works ok at idle or on the hose, but then slips more as you throttle/load it up when it needs to spin faster. Something cheap and easy to try anyway. I don't recall if you tried a different impeller.

[Kporsch]

There is a screen on the intake side of the transmission cooler. Did you check this for debris? I've had issues where it would allow enough water to pass at idle speeds but not enough at higher throttle. The trans cooler was full of junk.


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[LiquidObsession]

Have you tried a different impeller? It's possible the hub is slipping in the impeller (been known to happen on new ones occasionally) and that it works ok at idle or on the hose, but then slips more as you throttle/load it up when it needs to spin faster. Something cheap and easy to try anyway. I don't recall if you tried a different impeller.

Replaced 3 times last season... after each overheat incident. Will be putting in a new one again this season.

[LiquidObsession]

There is a screen on the intake side of the transmission cooler. Did you check this for debris? I've had issues where it would allow enough water to pass at idle speeds but not enough at higher throttle. The trans cooler was full of junk.


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Mechanic checked and said it was clean as can be however I will be checking it again myself... just to make sure.

[homer12]

Is it possible the water jackets in your block are clogged with something like old impeller bits or something? I know you can backflush your cooling somehow but I've never done that. Perhaps someone else has and could see if that's worth looking into


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[DW SD]

Pretty sure I already covered this but my mechanic looked at all of the possibilities leading up to the risers. We hit each potential component one by one.
-raw water inlet
-strainer (replaced w/ new high quality strainer)
-transmission cooler
-impeller
-pump
He told me verbatim what you said (risers? I seriously doubt it) but by the end of the season his last comment to me was ..."we've exhausted (pardon the pun) all of our options and I can't find the cause so looking at the exhaust would be our logical next step".

Your list didn't include thermostat. Maybe I missed a statement elsewhere that it was changed? That'd be one of the first items to change when over temp running is a symptom.
Is there a reason for internal crud (lime or corrosion)?
Did you leave salt water in it?

Removing the risers is four bolts and the two hoses. This is about 20 minutes for a top shelf mechanic.
I put the sealing surface on the riser on a large format belt sander to ensure a flat surface before installing. Scrape the exhaust manifold side with a razor blade. And clean up as best as possible. Get a new gasket too. It isn't hard to ensure a good seal.


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[H2O]

Another possibility, and a strong one at that, is the engine block circulating pump. As I recall, some coolant circulating pumps of that era were defective and failed prematurely. This is what is commonly called the "water pump" in your car engine. It is not the external pump in which you have already replaced the impeller. A relatively easy job but probably best left for your mechanic to replace (everything is always easy for the person not doing the work!).

[LiquidObsession]

Your list didn't include thermostat. Maybe I missed a statement elsewhere that it was changed? That'd be one of the first items to change when over temp running is a symptom.
Is there a reason for internal crud (lime or corrosion)?
Did you leave salt water in it?

Removing the risers is four bolts and the two hoses. This is about 20 minutes for a top shelf mechanic.
I put the sealing surface on the riser on a large format belt sander to ensure a flat surface before installing. Scrape the exhaust manifold side with a razor blade. And clean up as best as possible. Get a new gasket too. It isn't hard to ensure a good seal.


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First link in my post. Yeah... tested & changed that out to.
http://www.mbboatowners.com/index.ph...p-overheating/

No salt water ever. Run almost exclusively at Bullards Bar Reservoir.

[LiquidObsession]

Another possibility, and a strong one at that, is the engine block circulating pump. As I recall, some coolant circulating pumps of that era were defective and failed prematurely. This is what is commonly called the "water pump" in your car engine. It is not the external pump in which you have already replaced the impeller. A relatively easy job but probably best left for your mechanic to replace (everything is always easy for the person not doing the work!).

Mechanic told me it was good... but... being skeptical myself, how do I check it to assure it's working properly?

[DW SD]

I read your other thread. I believe if the block or risers were plugged, you'd not have run all day with your kids and then eventually had another issue. You'd have the issue all of the time. It seems your issue is sporadic, so I'd look elsewhere.

Given the symptoms I have two ideas:

1. I think the thermostat is sticking closed for some reason. Did you use a high quality PCM part (lots of junk parts out there)? I saw the one you tested and it looked brass. I think the OEM one has stainless housing (I forget, sorry). Get the one that opens @ 160F as you are supposed to have. Rather than one that open at a different temp. Next, check the thermostat housing and mating surface at the block. If something, say casting flash or other buildup puts stress on the thermostat itself, it might cause it to hang up when opening.

Also, one trick to making sure there is no air stuck behind the thermostat, which will prevent it from opening is drilling an 1/8" hole in the outer portion of the thermostat so air will bubble up through. even hot air won't transfer enough heat to open the thermostat.

2. The fact that you lost a serpentine belt prior, you smelled burning rubber and your water pump pulley looks like the belt might have been slipping on its pulley, (which wouldn't then provide cooling). I'd encourage you to remove the serpentine belt and manually crank each accessory. Look for one that is hard to turn.
If all good, perhaps your belt tensioner is failing and allowing the belt to slip. I'd then look at that and the tension it provides.

[homer12]

I think it might be time to pull your circulation pump and inspect it. I had to change mine in my old MC Ford 351. Mine was starting to leak and getting squeaky but still circulating water. On a vdrive a little harder to see and inspect without removing. I would think there is a metal kind of impeller in the middle of it that had a bearing or two in its shaft. It's possible that bearing is going bad or seizing and then the serpentine belt might be slipping over the pulley. Has your belt been shredded or torn up in these overheating episodes? Also, if you can run the engine before pulling this pump try to examine for it leaking water first


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[LiquidObsession]

I read your other thread. I believe if the block or risers were plugged, you'd not have run all day with your kids and then eventually had another issue. You'd have the issue all of the time. It seems your issue is sporadic, so I'd look elsewhere.

Given the symptoms I have two ideas:

1. I think the thermostat is sticking closed for some reason. Did you use a high quality PCM part (lots of junk parts out there)? I saw the one you tested and it looked brass. I think the OEM one has stainless housing (I forget, sorry). Get the one that opens @ 160F as you are supposed to have. Rather than one that open at a different temp. Next, check the thermostat housing and mating surface at the block. If something, say casting flash or other buildup puts stress on the thermostat itself, it might cause it to hang up when opening.

Also, one trick to making sure there is no air stuck behind the thermostat, which will prevent it from opening is drilling an 1/8" hole in the outer portion of the thermostat so air will bubble up through. even hot air won't transfer enough heat to open the thermostat.

2. The fact that you lost a serpentine belt prior, you smelled burning rubber and your water pump pulley looks like the belt might have been slipping on its pulley, (which wouldn't then provide cooling). I'd encourage you to remove the serpentine belt and manually crank each accessory. Look for one that is hard to turn.
If all good, perhaps your belt tensioner is failing and allowing the belt to slip. I'd then look at that and the tension it provides.

Some good thoughts and advice I haven't checked. Thank you. I had a horrible time with that whole thermostat thing. Different "theories" but no real "here's the link" help. Where can I purchase the factory PCM thermostat that's absolutely the real deal guaranteed?

Also, where can I purchase new exhaust hoses? Again, the good stuff.