wit's end

[Mo]

It's the one on the top side of manifold that goes into the exhaust. Remove that hose at the manifold end, carefully remove the fitting and clean it all out. Sometimes gung builds up there and restricts flow.

[damienk]

Thanks MO. On my way to the boat now and will do all we talked about. Last time I forced water inside the cooling system it exited from the fitting you are talking about with a very good flow, but still, I will remove the fitting and clean it to be on the safe side.
Will keep you guys updated tonight. Thanks a lot for all the ideas!

[JOHN COOKSON]

Now We're Getting Somewhere - I Hope Anyway

- 1 is a hose fitting, on the top on the same end as the thermostat housing. I believe it is part of the cooling system (it goes to my water heater, which is connected to the thermostat housing, and on pictures of other engines I saw it directly connected to the thermostat housing).

What's with the "water heater?" Do you mean HX (heat exchanger)? How about a picture or two? Are you RWC or FWC? I assumed FWC. Now I'm not so sure.
Maybe no coolant is being pumped through the HX.

TRUE GRIT

[damienk]

I'm on the boat right now. Shot a few videos and pics, will upload tonight from my laptop. Here is some information and answers to your questions:
-my gauge is now definitely shot. It was at max temp reading when I got to the boat, and it hasn't blinked since (after turning the engine on a fee times)
- my engine is a late model raw water cooler.
- the engine runs (now) but it still overheats.
- clamping the bypass didn't change anything
-the outflow from the manifold is excellent.
- I took temp reading with a gun: At the sensor, between 90 and 110. Top of engine block: About 120 after warming up. Manifold: Always warmer, was 160 to 180 when the block was at 120. At the exhaust hotpipe connection: From 220 and up to 300+ with white smoke after a while (steam I think) and a burnt smell.

Another information: I tried to blow inside the water exhaust hose exiting from the manifold (blowing out, not towards engine) and it was impossible. Too much pressure. I tried forcing water into it, it works but I get a lot of back pressure. Maybe normal, maybe not, I don't know? However, when all connected properly, the flow of water out of the exhaust is excellent.

I am going to upload pics as requested and comment them to the best of my abilities.

[ndutton]

Let's get the water heater out of the loop. Plumb from manifold outlet to the exhaust mixer for a test but if successful, add a siphon break for a permanent installation.

[damienk]

So far here is my reasoning:
- apparently the head and manifold have a great flow of water. This seems quite sure as I have a great and clean outflow, not too hot (felt warm on my hand, not burning hot). Also the head, manifold and side plate have all been taken apart and cleaned meticulously. So I think that I can rule out a bad water circulation inside the engine, despite the bypass clamp not reducing the temp.
- I assume I have a way too hot hot section. I doubt that temps in excess of 300 can be normal. And white smoke and burning smell (coming from connection between manifold and hot pipe) are not normal. This, for some reason, is overheating.
-what I don't get is how can this overheat if it is not where the water exits anyways? And hoe can it overheat if I do have great water outflow at the exit of the exhaust (outside the boat)? I don't understand the exhaust system enough to know what to do next.

[damienk]

Ndutton>> the manifold outlet is connected directly to the exhaust mixer. The water circulation goes as follows on my engine:
-raw water intake>water filter>water pump> T fitting (1 way inside engine through side plate, other is bypass hose) > bypass hose > thermostat housing > hose connected to my water heater/heat exchanger> hose coming back to the manifold inlet> manifold outlet connected to exhaust.
I checked each step separately and the whole thing together. I can blow water in any step of the way and it comes out clean with good flow anywhere I check, including when I check after the manifold. I also did the test bypassing the water heater/heat exchanger, but I am going to do it again right now with the engine on this time instead of just forcing water in.

[ndutton]

I'm leaning towards John's earlier thoughts. I'm not so sure you're overheating.

It seems the assumption is a 300° hot section is excessive and although I've never measured one, I don't think it's out of line at all. That's not much higher than boiling water. In fact, the ABYC table of allowable materials for gasoline engine hot sections specifies by footnote that carbon steel (by far the most common on our exhaust systems) is allowable only for temperatures below 900°F!!! The point being, they're talking about temps in an entirely different ZIP code than 300°.

When we were trying to include exhaust backpressure as an EWDS parameter we were looking for a pressure sensor that spec'd to at least 600°F. We found them but the vendors were awfully proud of them ($$$). With a little internet research, exhaust temps of 600° and considerably higher depending on mixture and RPM factors are common for gasoline engines

Your temp gun measurements seem in line everywhere else so maybe it's time to get a functioning temperature gauge before tearing things apart.

A side note about the hose routing
It's unusual in my experience for a water heater to be plumbed between the engine block and the manifold as yours is. You'll get more heat and better water heater performance if it's plumbed between the manifold outlet and the exhaust mixer. I incorrectly assumed yours was plumbed the conventional way.

[roadnsky]

I'm leaning towards John's earlier thoughts. I'm not so sure you're overheating.

It seems the assumption is a 300° hot section is excessive and although I've never measured one, I don't think it's out of line at all. That's not much higher than boiling water. In fact, the ABYC table of allowable materials for gasoline engine hot sections specifies by footnote that carbon steel (by far the most common on our exhaust systems) is allowable only for temperatures below 900°F!!! The point being, they're talking about temps in an entirely different ZIP code than 300°.

+1
Those readings are WELL within range.
I HAVE shot temp readings on my exhaust hot section.
At the top of the loop (and being wrapped) I've had top end readings of 480° during summer and 350° during cooler outside temps.

Why it smells hot and the white "smoke" though are disconcerting...

[Mo]

Your temps were fine. I check mine regularly with infra-red
-head usually around 102 for me and hotter near plugs.
-manifold 200-300 range...that will be normal.
-block will initially read around 140 or so but once the engine is running for hours it will be around 160.
-block will be hotter around the crankcase vent where the tube comes out the the carb...normal.
-after hours of running I found my temp around the carb, down low on the block around 150.
-oil pan ( even took a shot at that) sit around 150 under hours of use....keep in mind that oil is constantly running through the engine.
-side of the engine near starter and water intake side is around 140 regardless.

So the temps are up on the water jacket /carb side about 10 to 20 degrees because that manifold is sitting right there warming everything. I ran my engine about 7 hrs straight twice, weekend before last. I was keeping an eye on things and all was good. I run RWC, no T stat.

I'd like to relay a quick note: when I'm motoring I sitting directly behind the helm. I am listening for the exiting exhaust water...it's automatic. I mentioned I run with no T stat and by-valve half open...the above temps reflect that configuration on my engine. Prior to getting an infra red thermometer I alway removed the steps and put my fingers on the head....if I could hold them there the engine was doing fine. Just something to keep in mind.

PS: 3 weeks ago I towed a O'Day 34 back to the club (yeah, another Diesel) and it was in the water all winter because I could see the rim of jungle beneath it. Tow lasted a couple of miles and I did take shot at the engine with the infra read as Odyssey proceeded on autopilot with our tow. I knew the O'Day was back there because I could only make 4.2 kts in pretty calm conditions. It was at this point I figured I'd check the engine temp as all the horsies were up and at it. Block wasn't over 145 degrees at that time.

[damienk]

I have been asked to upload pics, here is one.

From left to right:
1st hose: going from manifold to my heat exchanger / water heater.
2nd hose: coming back from the HE/WH
3rd and 4th hoses: the curved one is the water intake, from the raw water filter to the water pump, the 4th one is the water exhaust out of the manifold.



This is my exhaust system. The hose going up is coming from the manifold, goes up quite high behind the wood panel then down again and connects to the riser (or whatever this aluminum hot pipe is called) right before entering the big white plastic box. Then, another hose goes out of the plastic box, and all the way aft outside the boat.

So, apparently I am not overheating (anymore, because this is probably what messed up my head gasket and fried my gauge and temp sending unit in the first place). I only tried with the by-pass hose clamped, so tomorrow I will try unclamped and see if the temperature rises or not. My gauge reading got me worried but I guess my temp gun is way more accurate (today the gauge did again what it did a couple days ago: it started working again and gave me a normal reading, then with no warnings and in a split second, jumped to max temp. Maybe a bad wiring? it. I will get a new gauge to be safe. I am relieved to hear that the exhaust temperature is within an acceptable range, but the smoke can't be normal. What can it be? It doesn't appear immediately: it starts very lightly after a few minutes of the engine being on, and then keeps increasing in quantity. It is not heavy smoke (you can see through very easily and it can actually be hard to notice it) but eventually it fills up the whole cabin with a very light smokescreen that smells very toxic. It does not start my very sensitive gas fume alarm, so I guess no gas fumes in this smoke. It comes precisely from the connection between the hot pipe and the fitting it is molded, and from the fitting itself (this fitting is connected to the manifold: there is no smoke coming from either the gasket or the manifold it self.
I think there is also some of the same smoke exiting the boat, but it is hard enough to spot inside the engine compartment, outside it gets blown away almost immediately (however, it is a lot of smoke inside, and I'm pretty sure it could do some serious damage to anyone staying inside the boat while the engine is on).
What do you guys think? I was thinking, if it isn't overheating, then maybe a leak or a clog in the riser? But is it normal to get this smoke at all (even exiting the boat)? I can't remember anything like that before (and definitely nothing inside).

I came a long way in a few days thanks to all of you guys. On Monday only, my boat wasn't starting at all. I appreciate the help

[hanleyclifford]

I notice that you are using the most restrictive of fittings. Why not try using straight connections to the manifold or at least cast style plumbers street fittings.

[ndutton]

Your gauge is acting like there's an intermittent short to ground somewhere along the wire.

[damienk]

Everybody > here is a link to a short video, so you can hear the engine running, and see the smoke by yourself. http://www.yourfilelink.com/get.php?fid=1095987


Ndutton > Thanks for the info! However if you want an idea of my electrical skills, I still look at light bulbs like it is magic. I am able to get away with it with logic and usually simply replacing/reproducing an existing system, but fixing a broken one... I will try, have a look at the wires, and see if I see something obvious. If you have a wiring diagram of what it should be like, I am interested, I can follow that. I lately found a few clues that something went wrong with my electrical systems but I am in denial:: my blower stopped working (I found a hot wire in my engine compartment that is linked to the blower switch, but no idea where it was connected before breaking lose) and I found another wire that is hanging lose connected on one end to the top of my coil where a bunch of other wires are also connected. I am pretty sure I never had wires hanging free before. Maybe it happened when I was fighting to remove nuts and bolts and studs all around the engine. But how can I fix something like that? The only way I could do it is with a diagram and checking every wire. Maybe the two free wires are actually meant to be connected to one another? I'm a little afraid to experiment with electricity, I would hate to damage something. Again, a diagram would come handy. But don't even say the word "multimeter" to me, at least not without a detailed step by step and child proof explanation of what to do with it.

Hanley > I will happily switch to better fittings if you can explain me what you are talking about. Maybe a link?

[ndutton]

May I ask where you're located?

This may be an excellent project to start your electrical career. Starting at the temperature sender, follow the single wire, usually tan, to the instrument panel where it connects to the 'S' terminal of the temperature gauge. Carefully inspect the condition of the insulation every inch of the way especially where it might touch anything metallic. Any damage to the insulation should be repaired with electrical tape at least. I won't ask you to replace the entire wire yet.

There are a number of drawings on the forum in their own category for ease of retrieval. Here is the diagram you're looking for.