cooling question

[Nick duBois]

I had a cooling problem last season and I thought the pump was the culprit. A friend rebuilt the pump last week and I installed it today. The pump works fine but I'm still having an overheating problem. I disconnected the hose after the thermostat housing before it goes into the manifold and the temp dropped from 195 to 125. It pumped a ton of water into the bilge. I then disconnected the hose from the manifold to the exhaust and the flow was considerably less. I assume there is a block in the manifold so I get a coat hanger and put it down the intake side of the manifold. I did not get much there and I'm scared straight to take the outlet fitting off. I tried but it's on good. I'm asking for any advice I can get. I have a compressor and thought of trying to blow the crud loose. How hard does the crud ( for lack of better term) get? will muriatic acid help. I'm under the impression that the manifold has two separate chambers and that if I fill it with acid it will not end up in the carb. Am I right? Looking for help....

Nick

[Al Schober]

Nick,
The outlet fitting on the manifold in a prime crud collector. You're going to have to remove that fitting from the manifold - even if you have to use a saw and a drill! First step is a bigger wrench - think 'big pipe wrench' and 'extension pipe' - you get the idea. Don't go 'saw and drill' until you've totally ruined the fitting. Partially ruined is not a big deal as long as you get it out - a replacement fitting isn't expensive.
While doing this, you may want to consider re-routing the plumbing. Out of t-stat housing to LOW end of manifold, out the HIGH end of the manifold to the exhaust system.
Hope this helps..

[marthur]

Does anyone on board have experience dissolving "crud build up" with an acid flush? Just wondering if it is a viable alternative for this situation.

[Nick duBois]

I thought of filling the manifold with acid to see if it would work. I did a flush last season and it worked great them all of a sudden my engine temp started to rise at the end of the season. It did so almost overnight.

[ndutton]

Does anyone on board have experience dissolving "crud build up" with an acid flush? Just wondering if it is a viable alternative for this situation.

Depends on the crud. My first acid flush produced an incredible black plume out the exhaust accompanied by an awful organic sewery smell. My second acid flush just prior to FWC conversion not so much followed by opening the water jacket for a good scrape and water jet. It looked pretty good in there so I surmised the first flush did a decent job.

On the other hand I acid flushed my spare engine prior to opening the water jacket with nowhere near the effluent production. Removing the sideplate I could not tell there was an opening underneath. It was solid as a brick and even with the block face. What worked for me was a pneumatic needle scaler and about two hours of careful archaeology work.

So I'd say if the crud is still in the primordial goo phase an acid flush should be effective. If it's petrified it'll take a more aggressive approach. Please be advised however that muriatic acid eats away at our irreplaceable and therefore precious metal. Follow Don's dilution and soak duration recipe and be further aware that swimming pool acid is already diluted so you'll have to do a little math to get it right.

[Al Schober]

Nick,
An acid flush has little affect on hard build-up. I had one manifold with known hard build-up. Sighted it visually after removing the core plugs, so I could watch visually the affect of the acid. Like water off a duck's back.
I suspect your acid flush last fall loosed stuff up a bit, and those pieces have migrated to the manifold exit. Remove the exit fitting - see earlier post.
I had a case of overheat while up the St John River (NB), and found a collection of crud right under the thermostat (removed crud and thermostat).
If you have any doubt it's the manifold, try blowing through it. Until it blows easily, you still have a problem. You can try acid flush for a week, or remove the outlet fitting and be done in an hour - your choice.

[Nick duBois]

Nick,
You can try acid flush for a week, or remove the outlet fitting and be done in an hour - your choice.

Ok Al,you have convinced me I will do the deed tomorrow. I have PB Blaster soaking the fitting now. I have had good luck with this product so we will see.

[Dave Neptune]

Vinegar 1st

Nick, I have had good luck with using a vinegar soak when the build up is not to bad. A 2~3 day soak does wonders. If the soak and/or cleaning under the exit fitting (a common problem) then a messy and more work of an acid wash may be in order.

Dave Neptune

[Nick duBois]

A 2~3 day soak does wonders.
Dave Neptune

Can I fill that manifold with vinegar without problems? There is no way that the water part mixes with the exhaust part right?

[Dave Neptune]

Patience

The only way they mix is if there is a hole then it does not matter. The vinegar is a lot more gentle and takes more time. Just fill one side until it comes up on the other end and let it sit. The boat will smell like a salad instead of an out house .
Did you find any KRAP under the exit fitting?

Dave Neptune

[Nick duBois]

I'm going to try to take the exit fitting off in a few minutes....Fingers and toes crossed. My Catalina 27 does not give much space in the to work so if it breaks then it's a whole other ball game.

[JOHN COOKSON]

If All Else Fails

I then disconnected the hose from the manifold to the exhaust and the flow was considerably less. Nick

I assume there is a bit of flow through the manifold.
Fill a bucket with vinegar or very diluted muratic acid. Toilet bowel cleaner might work also. Attach a hose to both ends of the manifold and lead them into the bucket. Attach a pump to one hose and pump the liquid through the manifold.
Also you can try reversing the present inlet and outlet to see if you can back flush the crud out.
Try smacking the outlet fitting with a hammer as you wrench it - might help break it loose.

TRUE GRIT

[Nick duBois]

I'm back from the boat and it seems I was able to fix the problem. I got the fitting off without too much trouble. It was partially clogged with crud and there was crud under it in the manifold. I used a coat hanger to loosen it up and then put the shop vac on the hole. I heard some more stuff being sucked up. I then took out the compressor and blew out the manifold by placing my thumb on the exit hole and the air hose on the intake fitting letting the pressure build and holding until the pressure blew my thumb off. I did this several times and stuff flew out the hole. I know the manifold holds pressure now lol. I put it back together and fired her up. I now have lots of water and without a t stat cant even get the temps over 100. a big thanks to all who helped out. I'm still going to soak some vinegar in there for a few days just to be safe.