Optimal Running Temp/Pressure?

[Tkenopic]

Can't thank everyone here enough for all their help!

You may have seen in recent threads, you have helped me solve a dirty fuel issue, tank cleaning, Racor filter installation, and sticking valves. Now the boat is running!

What I noticed now is that both the oil pressure and water temp seem higher than before. They were consistently Running around 40 PSI for the oil which is now at 60 PSI. The water temp was running around 160, but now it is 180. These values are at idle. There also seems to be a fair amount of smoke in the exhaust, which from reading other threads may come from adding the MMO to the valves and fuel.

So here are a few questions:
1) Is there an optimal running temp/pressure or is every boat different under different conditions?

2) At what point should I be concerned about temp/pressure being too high?

3) What could be causing the higher temps/pressure?

4) What should I do about it? I've read elsewhere about treating the cooling system with vinegar, but for the life of me can't figure how or where to do that?

Here's a photo of gauges (from when boat was on hard) and a short video so you can see the type of water pump (it's lake-water cooled). I'll have to use links until I figure out how to add photos/videos in the forum - sorry!

https://goo.gl/photos/umBqik8yFGz6F7178

https://goo.gl/photos/azpV3wuyaekvRRAC7

Thanks in advance!
Trevor

[edwardc]

...I'll have to use links until I figure out how to add photos/videos in the forum ...

When you're composing your post, scroll the page down below the text entry box. There's a button labeled "Manage Attachments"

[BunnyPlanet169]

It's always fun to hear a success story - nice work!

Your questions cover huge areas of A4 maintenance. It's like you just pitched a big slow softball at us...

First - if you haven't, run, don't walk, and get the MMI manual. It covers everything you need to know, including nominal running conditions and trouble shooting.

Second - from your pictures - please consider replacing the valves with proper sea cocks. Gate valves do not obviously show open/closed, and fail regularly. They are not appropriate for boats.

Your questions:

1) yes and yes. So many variables. Broad strokes - 160 on the water, 40 on the oil. Variables: are you using a thermostat? Idle or running hard. Bypass loop. Cooling water inlet temperature. Etc. Oil pressure is adjustable. On the oil, I don't know what too high does, 40-60 is great, and too low is maybe <20 psi. Again, dependent on RPM and operating temperature.

2) Water: Depending on thermostat and bypass, but anything over 180 without a FWC heat exchanger is suspicious. I had issues here, and 180/190 is awfully close to boiling, at which point you are already in thermal runaway. By the time the sensor is reading over 180, other parts of the block are probably hotter, especially in a compromised flow situation. Which is bad, BTW.
Oil: MMI recommends 40 psi nominal at RPM - there is a lot of variation on this forum - anything over 60 and I would adjust down.

3) Lets start with oil this time: The only reason I know for oil pressure to climb is gunky blocked passages. Did you do an oil change? I can't comment on this knowledgeably, but there may be some value in a oil change/flush process where you deliberately dilute the oil 25% with diesel fuel/MMO/kerosene, run it for a bit (time anyone?), just to flush out the oil galleries. Then change again. And maybe again.

Water: There are several places the A4 can have issues with the water cooling, especially on a RWC engine. Basically, starting with the water pump... Impeller? How new? Then follow the water (and check flow into a bucket) through the engine. Engine block can become encrusted on the inside, the head can get encrusted, the thermostat may not be functioning, the exhaust manifold can be encrusted.... There are many epic and informative threads on the forum on this topic.

4) Engine flush with vinegar. Go to Cooling Systems on the forum topics and search. Here's a good start: http://www.moyermarine.com/forums/sh...pressure+flush Post 39 has a pdf of the official procedure for acid. Use full strength household vinegar to start.


Good luck!!

[ndutton]

180° at idle sounds high, will likely increase another 30° or more under load. The remedy for lower temps is more flow, most thoroughly achieved with an acid flush perhaps along with removal of the side plate and physically mucking out the water jacket. Removal and inspection of all external elbows, exhaust injection fitting, addition of a bypass valve and in an extreme measure, removal of the thermostat will all contribute to increased flow. Thermostat removal is required for the acid flush anyway so have some gaskets on hand. If you decide to remove the sideplate you might consider replacing the bolts with MMI's sideplate stud kit.

Oil pressure
60 PSI is getting up there. Fortunately there is a pressure adjuster on the side of the block, under and a little aft of the carburetor.

[Tkenopic]

Your questions cover huge areas of A4 maintenance. It's like you just pitched a big slow softball at us...

First - if you haven't, run, don't walk, and get the MMI manual. It covers everything you need to know, including nominal running conditions and trouble shooting.

Thanks Jeff,
You are right, I am discovering more and more that there are so many things to learn and do. I will definitely get the manual. I'd like to put together a large-ish order list so that I don't have to re-order supplies. I remember seeing a spare parts order list somewhere on here, I'll have to dig around and find it. Thanks for your help and suggestions, that link to the acid flushing is great!

Is there a way to save posts to keep track of them, like a favourite's or book mark?

[Tkenopic]

180° at idle sounds high, will likely increase another 30° or more under load. The remedy for lower temps is more flow, most thoroughly achieved with an acid flush perhaps along with removal of the side plate and physically mucking out the water jacket. Removal and inspection of all external elbows, exhaust injection fitting, addition of a bypass valve and in an extreme measure, removal of the thermostat will all contribute to increased flow. Thermostat removal is required for the acid flush anyway so have some gaskets on hand. If you decide to remove the sideplate you might consider replacing the bolts with MMI's sideplate stud kit.

Oil pressure
60 PSI is getting up there. Fortunately there is a pressure adjuster on the side of the block, under and a little aft of the carburetor.

Thanks! I'll use the acid flush link to help figure that out, as well as ordering the manual...

[Tkenopic]

Second - from your pictures - please consider replacing the valves with proper sea cocks. Gate valves do not obviously show open/closed, and fail regularly. They are not appropriate for boats.

Will do! Winter lay up is just around the corner and will add this to the already long list of chores!

1) yes and yes. So many variables. Broad strokes - 160 on the water, 40 on the oil. Variables: are you using a thermostat? Idle or running hard. Bypass loop.

Thermostat: short answer is I don't know. I'd assume so since I have a gauge telling me the temp? But I'm not sure on the location. Seeing the posts about flushing saying to remove thermostat first, I'm having a hard time figuring out where it is, and no idea about the bypass loop...such a noob I am!

[Tkenopic]

OK, thanks again for all the help. I've printed off some of the posts, pdf's, and pics. Headed down to the boat to try out the flush. Will report back!

[Tkenopic]

So when I went to do the cooling flush, the first thing I noticed is that pump did not want to draw in the muriatic acid solution. I lowered the bucket and tried to work out the air bubbles. The engine started running really hot so I shut it down. Re-positioned the bucket and fired it back up. It drew about half the bucket but then water out the back really slowed down. Concerned about the temp, I shut it down again and went looking for other problems.

Sure enough, as suggested in Don's checklist, there were major problems with the impeller (pictured). The little bits were jammed up into the outlet. Fortunately I had a spare on board and changed it out. Presto! Temp came way down and no more steam.

Have a couple vids, but phone is not cooperating right now...

Other pic is the lowered temp on the gauges after the impeller change and the cooling system flush. Oil pressure is still kind of high. I have recently changed the oil, and yesterday added a bit of MMO to the oil. Pressure seems to drop to around 40 once I put the boat in gear.

Thanks again for all the help!

[ndutton]

You're not done yet

So far so good but for a complete repair it is imperative you remove and examine the plumbing elbows throughout the cooling system, particularly the one at the rear of the manifold. Wouldn't hurt to remove and check the thermostat too. What you're looking for is impeller bits that have migrated throughout the system and lodged themselves in catch points.

Personally, I'd pull the sideplate to check the diverter, muck out the water jacket while I'm in there, install studs on reassembly. In other words, make it as good as possible.

[Tkenopic]

So far so good but for a complete repair it is imperative you remove and examine the plumbing elbows throughout the cooling system, particularly the one at the rear of the manifold. Wouldn't hurt to remove and check the thermostat too. What you're looking for is impeller bits that have migrated throughout the system and lodged themselves in catch points.

Will do, thanks for the suggestion!

[BunnyPlanet169]

Nice Job, Trevor!

Since you're new to the A4 - here's a snip from the panoramic view of the engine found on the home page.

1 is (usually) the last manifold elbow that Neil is referring to. You may find your engine is plumbed from 2 (the thermostat) to 1 (rear exhaust manifold) and the last plumbing fixture is then on the other end of the manifold. This alternative plumbing is called "The Thatch" for it's inventor on this forum. Either way, the last elbow is where we often find crap in the cooling system.

2 is the thermostat housing. Two nuts which may or may not look like this picture - there are MMI aftermarket options here I won't go into. Inside, you'll find the thermostat which is removable by hand.

3 is the bypass loop. It comes from the pump outlet, puts some water into the block water jacket, and allows some water to flow around the thermostat to keep the exhaust cool while the engine is warming up. You may or may not have one, and it may or may not include the manual valve.

[sastanley]

Trevor, it is daunting, but keep up the good work..everything here is well advised.

Simply attack each task individually, as small as it seems..they all help. I think it is the best recipe for ultimate success.

I am a little bit out of the loop but have you tried to re-construct the impeller pieces to see if you have all the pieces??..this is what Jeff and Neil are eluding too...you can't let anything go rogue or it may get lodged into some place that reduces cooling flow.

Continue to feed us as many details as you can so we can help.

[thatch]

Rather than just give a "thumb's up" to Shawn's post, and to what Jeff and Neil have said, I will go one step farther and say that I feel that it is very important that all of the impeller parts are found, particularly the ends of the vanes. It is very common for these pieces to head "down-stream" and stop at the first "right-turn". One other "process" that I use while going through the cooling system of a raw cooled engine is to use a "tack hammer" in conjunction with probes to free up the scale deposits in the water passages. After completely drying the cast iron pieces involved, I use a light tap,tap,taping around the entire outside of the piece, which tends to loosten much of the restricting stuff, including "rust cornflakes".
Tom

[marthur]

I can testify to that! It is possible for one of those impeller bits to come unstuck years later. My PO had an impeller die and the rubber piece blocked the fitting at the exhaust manifold (effectively blocking the flow of water) 4 years after I bought the boat.