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Old 07-11-2012, 06:13 PM
wmmulvey wmmulvey is offline
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Exhaust manifold problem re-post w/pic's

1969 A-4 Late model w/RWC system in salt water.
Pic’s to follow at end of post

PART ONE
Good water flow out the exhaust

Using a IR temp gauge

1. Engine block side of the manifold at good temp all around the block.
2. Upper part of the manifold temp around 190
3. Lower part of the manifold smoking and temp over 300 in a very short time.

My opinion is that part of the water passage is clogged.

PART 2
Bought a used manifold and as per Moyer instructions, with some changes did:

1. Filled the input/output ports with Mauriac acid (lot of foaming) and let
stand overnight.

2. Flushed and neutralized

3. Plugged the input/output ports

4. Removed the drain plugs and the freeze plugs and filled with Mauriac
acid (lot of foaming) and let stand overnight.

5. Flushed and neutralized

6. Using a coat hanger probed all openings and flush and repeat several
times until no more garbage came out.

7. Replaced freeze plugs and fittings.

PART 3

Removed the original manifold and installed the used one with new gaskets.
Fired it up, good water flow out the exhaust, and had the same problem as in PART ONE.

PART 4

I intend to use the same procedure with the original manifold as in PART 2. After that Intend to get it professionally flushed.

How do I get this done and who would do this kind of thing?

I have heard of hot tanking but have no info on this or how it works.

Hope I was not to long winded but really had to explain the steps I followed.

ORIGINAL MANIFOLD



FLANGE SIDE BURNT



FLANGE SIDE TOP VIEW BURNT


INTAKE/EXHAUST SIDE BURNT BELOW PORTS



TIA FOR YOUR HELP.

Regards
Bill
Home Port NJ

Last edited by wmmulvey; 07-12-2012 at 12:50 PM.
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Old 07-11-2012, 06:46 PM
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cant see the pictures
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Old 07-12-2012, 10:29 AM
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Old 07-13-2012, 01:05 PM
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Photos updated
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Old 07-13-2012, 01:40 PM
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Quote:
Originally Posted by wmmulvey View Post
1969 A-4 Late model w/RWC system in salt water.
Pic’s to follow at end of post

PART ONE
Good water flow out the exhaust

Using a IR temp gauge

1. Engine block side of the manifold at good temp all around the block.
2. Upper part of the manifold temp around 190
3. Lower part of the manifold smoking and temp over 300 in a very short time.

My opinion is that part of the water passage is clogged.
This sounds normal to me. The water jacket in the manifold really only covers the top half or so of the manifold and I think it's just one straight passage. The lower part of the manifold is always hotter, particularly at the front corner (UHS). If you cleaned it out well and are getting good water flow through it, that's about all you can do.

From your photos it looks like maybe your gaskets were leaking a little. Did you ever observe any smoke?
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Old 07-13-2012, 02:21 PM
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Bill,
This is not an official endorsement, however, some of us have changed the flow of the manifold by running the t-stat housing hose down to the bottom of the manifold and then run the forward manifold hose to the exhaust mixer..forcing water uphill thru the manifold rather than downhill...it is unofficially called the "Thatch modification", after user thatch that pioneered it..

What is the temp gauge reading on the engine?
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Old 07-13-2012, 03:49 PM
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Quote:
Originally Posted by wmmulvey View Post
1969 A-4 Late model w/RWC system in salt water.
Pic’s to follow at end of post



PART 2
Bought a used manifold and as per Moyer instructions, with some changes did:

1. Filled the input/output ports with Mauriac acid (lot of foaming) and let
stand overnight.


2. Flushed and neutralized

3. Plugged the input/output ports

4. Removed the drain plugs and the freeze plugs and filled with Mauriac
acid (lot of foaming) and let stand overnight.

5. Flushed and neutralized

6. Using a coat hanger probed all openings and flush and repeat several
times until no more garbage came out.

7. Replaced freeze plugs and fittings.

PART 3

Removed the original manifold and installed the used one with new gaskets.
Fired it up, good water flow out the exhaust, and had the same problem as in PART ONE.

PART 4

I intend to use the same procedure with the original manifold as in PART 2. After that Intend to get it professionally flushed.

How do I get this done and who would do this kind of thing?

I have heard of hot tanking but have no info on this or how it works.

Hope I was not to long winded but really had to explain the steps I followed.



TIA FOR YOUR HELP.

Regards
Bill
Home Port NJ

You let the part stand in muriatic acid overnight???

I'm surprised you even have a part left.

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Old 07-13-2012, 03:54 PM
dthibaul dthibaul is offline
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Hot tanking

Bill,

As far as getting the manifold "professionally" de-gunked, you may be talking about what used to be done at radiator shops to old car radiators and referred to as "boiling". I was replacing the hot/wet side this past year and decided to remove/acid flush the manifold and for extra measure went looking for a radiator shop. Not too many of them exist any more, and if they do, they don't boil units anymore (just replace the whole thing). I was traveling every week to Muncie IN and happened to find a radiator shop that still boils and had it done (interesting looks from TSA as it went through x ray). After all was said and done and re-installed, there was a breach between one of the hot chambers and wet chambers of the manifold causing water intrusion into the oil. This may have been caused by too agressive an approach with the acid, or the boiling- hard to tell. I just bought a new unit from MM and all is well now.

Don
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Old 07-14-2012, 10:18 AM
wmmulvey wmmulvey is offline
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Quote:
Originally Posted by Loki9 View Post
This sounds normal to me. The water jacket in the manifold really only covers the top half or so of the manifold and I think it's just one straight passage. The lower part of the manifold is always hotter, particularly at the front corner (UHS). If you cleaned it out well and are getting good water flow through it, that's about all you can do.

From your photos it looks like maybe your gaskets were leaking a little. Did you ever observe any smoke?
300+ degrees is not normal. According to the cooling diagram on Pg 26 of the A-4 manual, there are 2 water passages.

There was smoke from burning paint. No exhaust smoke.


Last edited by wmmulvey; 07-14-2012 at 10:33 AM.
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Old 07-14-2012, 10:28 AM
wmmulvey wmmulvey is offline
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Quote:
Originally Posted by sastanley View Post
Bill,
This is not an official endorsement, however, some of us have changed the flow of the manifold by running the t-stat housing hose down to the bottom of the manifold and then run the forward manifold hose to the exhaust mixer..forcing water uphill thru the manifold rather than downhill...it is unofficially called the "Thatch modification", after user thatch that pioneered it..

What is the temp gauge reading on the engine?
I will try the "Thatch modification". Can't hurt.

I did not look at the temp gauge.

I used a IR hand held thermometer and measured the temp at all points of the block and head. All temps were in the normal range.
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Old 07-14-2012, 10:53 PM
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Question

Have you considered the possibility that the block could be blocked in just one or two places, allowing water to get thru, but bypassing some areas?
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Old 07-15-2012, 10:53 AM
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Quote:
Originally Posted by hanleyclifford View Post
Have you considered the possibility that the block could be blocked in just one or two places, allowing water to get thru, but bypassing some areas?
I have a bypass valve setup.

I ran the RW directly through the thermo to the manifold inlet.

I switched, closed it and ran directly through the block.

I switched and ran it through both.

The results were still the same.

Again all............THANKS FOR YOUR HELP
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Old 07-15-2012, 01:04 PM
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Quote:
Originally Posted by wmmulvey View Post
According to the cooling diagram on Pg 26 of the A-4 manual, there are 2 water passages.
I would not give too much significance to that diagram - it's just a pictorial/diagrammatic represention showing general water flow. I don't think it's mean to be a literal schematic.

It's not so much that there are distinct "passages" for the water - rather, the rectangular outside shape of the manifold, very much like the block itself, is a "jacket" that surrounds the intake and exhaust passages.

Picture your typical exhaust manifold:



Now of course, ours are a combined exhaust/intake manifold, but this is just for general purposes here.

Anyhow, now imagine you want to surround that manifold shape with water. So you put a box around it. The space in between the interior intake/exhaust "pipes" and the outer "box" (jacket) is where the water flows through.

The only thing I can't specifically recall is whether there is a jacket space on the side of the manifold that is up against the block. It might be the case that there is less of a jacket space on that side of the manifold.

The only thing I can think of - and mind you, this is a total SWAG - could you possibly have a little ignition timing issue? I'm totally theorizing here, but it seems to me that if your timing is a bit too advanced, you would get ignition before the exhaust valve is closed, causing part of the explosion to be blowing out the exhaust. Like I said, I'm just totally skylarking/theorizing here.
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Old 07-15-2012, 04:44 PM
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You might find this thread interesting.

Among other things, there's a photo of a manifold cut in half showing the L-shaped water passage that runs along the top and side of the manifold. I believe that is the only water passage.
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Old 07-15-2012, 05:00 PM
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The engine block internally offers a number of paths for cooling water to take from the injection point to the thermostat housing even with the bypass closed. Just because you are getting good flow thru to the exhaust does not mean that your block is not plugged in some areas and simply offering preferential flow for the water.
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Old 07-15-2012, 07:10 PM
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Well it certainly seems that water flows only along the "outside" surfaces of the manifold, so that the portion closest to the block does not have a water jacket and is instead a solid casting. So it would make sense that that side will be significantly hotter than the outside surfaces.
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Old 07-15-2012, 08:13 PM
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Quote:
Originally Posted by ILikeRust View Post
Well it certainly seems that water flows only along the "outside" surfaces of the manifold, so that the portion closest to the block does not have a water jacket and is instead a solid casting. So it would make sense that that side will be significantly hotter than the outside surfaces.
Exactly, and if there were a jacket blockage in that area it would only be manifested by localized overheating while water flowed elsewhere thru the block.
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Old 07-15-2012, 09:14 PM
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This "problem" would be easily solved if we would all use Hi-Heat BBQ paint on our exhaust mainifolds...as I have recently done.

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Old 07-17-2012, 10:19 AM
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Quote:
Originally Posted by Loki9 View Post
You might find this thread interesting.

Among other things, there's a photo of a manifold cut in half showing the L-shaped water passage that runs along the top and side of the manifold. I believe that is the only water passage.
Is that another water passage on the bottom?
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Old 07-17-2012, 12:51 PM
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I think what you are looking at is the intake passage.
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Old 07-17-2012, 03:40 PM
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Here's my interpretation:



Thanks to the original photographer for the manifold postmortem.

The UHS occurs because the water jacket doesn't completely cover the #1 exhaust port and the water flow in that corner of the jacket probably isn't very good.
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Old 07-17-2012, 09:27 PM
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I wonder if better cooling could be achieved around the UHS if the coolant was directed thru the forward expansion plug rather than the 1/2" NPT hole on top of the manifold.
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Old 07-18-2012, 10:43 AM
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Exhaust manifold problem re-post w/pic's

I went out to the boat yesterday to try the "Thatch modification" (on the used manifold) that Shawn suggested.

I took off the t-stat housing to change the hose but decided to just remove the t-stat and see what happens. I did not do the "Thatch modification"

PROBLEM SOLVED.......Bad t-stat

Instead of 300 + degrees the temp went down to 220. After running for about 15 minutes the temp went down to 190 and no hot spots. Seems like the water pressure pushed out some loose gunk leftover from the mauriac acid cleaning.

Thanks for all your help. I sure learned a lot from all the discussions on this thread.

Bill
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Old 07-18-2012, 02:40 PM
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"Heartbroken"

Bill,
I am crushed that you decided not to convert to the "thatch" hose route.
Actually, my approach to plumbing an engine comes from several years of building cooling systems from scratch and running the hoses according to things like heat and gravity. Most of the A4s still running, are plumbed the way that they came from the factory and are doing just fine. My change on the A4 involved mainly two things. First, by running the coolant (water or coolant) into the lowest port of the manifold, you minimize the possibility of air pockets as much as possible. Secondly, by injecting the coolant coming from the block to the potentially hottest point of the manifold where the gasses from all 4 cylinders are passing, you may be able to "stabilize" the overall temperature of the manifold. In the stock configuration, the coolant is injected very close to the exhaust port of cylinder #1 and is then is being asked to cool cylinders 2,3 and 4 on it's way down the line. By reversing the flow I feel that it is possible that some minor "longevity" benefits may be gained. At this point in time, where all of our engines are over 30 years old, the most important thing is to make sure that there is still adaquate coolant flow to cool things down. I am a firm advocate of the fresh water conversion to lengthen the life span of these wonderful little engines.
Thatch
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Old 07-18-2012, 05:31 PM
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Thumbs up Heads up

Bill, if you just acid flushed I suggest that you pull the "exit" fitting where the water comes out to go to the exhaust. It is a common spot for debris to collect after flushing or digging around in the coolong system. I'd take a look after an hour or two of running to see if anything has been collected there. Worth a look if your "not sure".

Dave Neptune
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Old 07-18-2012, 06:33 PM
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Descaling

To expand on what Dave said, normally during a rebiuild involving an old block, I will "tap away" with a "light weight" hammer around the exterior, trying to loosten up the scale buildup in the water jackets as much as posible. Many times the pieces that break loose are big enough to plug the water fitting holes. By using screw drivers, coat hangers and other probes, it is normally possible to remove a considerable amount of "junk". Having the block as dry as possible during this process generally yields the best results.
Tom
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Old 07-19-2012, 09:47 AM
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