CAT 3306 overheating

I have done a barnacle flush on the sea water circuit using Rydlyme, over the weekend.
The flush was successful. The idle temp went down. However, the engine still overheats at cruising rpm, which is 1500.
At 700 rpm idle, the temp is steady at 160F. In reverse gear, idle rpm 700, the temp is 175-180 and steady. When I put it in neutral and go up with rpm, it is 180 at 1000 and 1200, but at 1500 it overheats to 210/220.
At this point I ran it on idle for 5 minutes to cool it down and turned it off and started again. It was 180 at idle rpm. I am afraid to take her out and have the engine overheating, while cruising. Your opinion? Thanks

You have addressed just one of several possible causes of engine overheating. Others, in no particular order, are:

1. Sea water flow is reduced due to a restriction in the suction side of the pump: collapsed hose insides, barnacle fouling of the hull inlet, strainer plugged with sea weed, etc.

2. Impeller is bad or pump body is worn reducing flow.

3. Main heat exchanger is plugged with old zincs or marine growth.

4. Injection elbow is plugged with scale reducing flow.

5. Antifreeze coolant side is fouled.

6. Coolant side pump is bad

7. Coolant side thermostat is stuck closed

The list goes on. But don't just start tearing things apart and cleaning or replacing stuff, although that may be a good idea for an old engine with neglected maintenance. Most of these can be ruled in or out with intelligent diagnostics with limited tools like an IR gun.

David

DavidM said:

The list goes on. But don't just start tearing things apart and cleaning or replacing stuff, although that may be a good idea for an old engine with neglected maintenance. Most of these can be ruled in or out with intelligent diagnostics with limited tools like an IR gun.

David

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Thanks David.

I have a longer history about this problem on this other thread:
https://www.trawlerforum.com/forums/s6/muddy-cat-3306-a-50977-3.html#post897230

I started a new one, because this time the issue might not be the sea water circuit. I have replaced the thermostat, the temp sender, and the sea water pump. I did the barnacle flush on the sea water circuit.

It seems the problem is with the coolant flow. It is enough for low rpm, but at high rpm, like cruising speed, it is not.
I am looking for ideas, how to narrow it down? Belts, or water pump?

I fixed overheat problems in a number of engines with a similar history of work done. Often the need to flush the coolant side gets overlooked. When the coolant gets old, the anti-rust properties are lost. Rust can form on the water jackets and passages in the block and head. It acts as insulation. So less heat is transferred from the engine to the coolant until the heat rise is uncontrollable. Rydlyme also dissolves rust. It's a quick, easy operation to try before throwing more parts at the engine. It's worked for me many times. Since the engine doesn't overheat at idle, running a couple hours at 160°F will speed up the cleaning.
One more thought, too high of a antifreeze mix doesn't transfer heat as well as water. Using 100% antifreeze can lead to overheating.

Lepke said:

I fixed overheat problems in a number of engines with a similar history of work done. .

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Lepke

If I understand you correctly, you would do a Rydlyme flush on the coolant circuit, as well? Am I correct?

Do you have any advice, how to collect the coolant safely, without letting it into the bilge? I am on the hook full time and it is difficult to maintain a dry bilge.
Thanks.

Lepke said:

. Rust can form on the water jackets and passages in the block and head. It acts as insulation. So less heat is transferred from the engine to the coolant until the heat rise is uncontrollable.

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Do you see any rust inside the coolant pipe on this photo?

Lepke said:

I fixed overheat problems in a number of engines with a similar history of work done. Often the need to flush the coolant side gets overlooked.

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Lepke
Do you know where the drain plug is for the coolant on a 3306? Is there one on the block, or somewhere else? I cannot figure it out from the manual.
Thanks.

I don't know the 3306 very well. Since you have been into the coolant side is it possible for the circ water pump to be full of air? Most engines are self bleeding but some are not.

Belt driven or gear driven circ pump? Seen pumps where impeller slipped off shaft. Looked all normal, but would not pump.

With engine warmed up to where tstat starts to open, you should be able to sense coolant flow beginning. Pipes leading to HX should warm up, HX should warm up a bit on one end.

If the HX is fouled on either side (or both), coolant at exit will be hot where it leads to circ pump suction.

Usually the exhaust manifold and turbo (if water cooled) are on a separate flow path that does not go through the tstat and HX. So as engine warms up those two things should warm up uniformly and their plumbing should warm up indicating flow. If manifold warms up but plumbing stays cool that means no flow.

That it is overheating at such low power setting makes me want to verify the circ pump is doing its thing.

Ski in NC said:

That it is overheating at such low power setting makes me want to verify the circ pump is doing its thing.

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I suspect it is gear driven circulation pump. I looked at it this morning and I don’t see a belt going to the pump. I suspect I know which is the circulation pump, but I was not sure. I took some photos. I see a plug at the bottom of it, so it could be the draining spot for it.
I really want to descale the coolant system, before I do further troubleshooting.
The belts you see on the photos are the alternator one on the left and the hydraulic pump on the right. The water pump must be the one above the hydraulic pump and part of the block. That is my guess.
See photos.

LeoKa said:

Lepke

If I understand you correctly, you would do a Rydlyme flush on the coolant circuit, as well? Am I correct?

Do you have any advice, how to collect the coolant safely, without letting it into the bilge? I am on the hook full time and it is difficult to maintain a dry bilge.
Thanks.

Click to expand...

Yes, I'd use Rydlyme on the coolant side. It dissolves rust. Rydlyme is biodegradable so I pump it over the side. On my engines, I installed a small valve on the block drains so I can connect a hose, circulate, drain, etc. On the Detroits, before the block drain valve, I have a builtin pan under the engines and drain the antifreeze into that and then pump into a bucket. Now I just run a hose to a bucket. If you're fast when the engine is cold, you can pull the plug and install the valve without a big loss of coolant.

When I was a fisherman, in warmer waters, many didn't use antifreeze, just an anti-rust additive and water. Those that let the anti-rust additive get old had overheat problems and had to do a coolant flush. Just like maintenance on a car, the coolant side needs a flush at times.


It sounds like you've done all the common fixes for overheat in the raw water side. If you have a good thermostat, good exhaust water flow, and recent flush, it has to be a coolant side problem. But, since the idle temps went to normal after the flush, but not cruising, it's remotely possible you need an additional raw water flush.
Raw water flow is important. I have seen barnacle and mussel growth inside plumbing close to the seacock. Also in a ship used seasonally, I had mussels in the plumbing, die when the ship was laid up in fresh water, and then come loose and plug the strainer the first time the engine was started after layup. Since that experience I've always added a way to force out the salt water with fresh and close the seacock when laying up.

Leo
Two questions
--When was the last time the engine and transmission coolers were removed, cleaned, inspected and pressure checked?
--Has this engine ever run at full rated RPMs without overheating?

sunchaser said:

Leo
Two questions
--When was the last time the engine and transmission coolers were removed, cleaned, inspected and pressure checked?
--Has this engine ever run at full rated RPMs without overheating?

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I have removed the transmission exchanger 2 weeks ago and could not see any blocking stuff there. Just last week, I did the Rydlyme flush, when the mix was sitting all night in the sea water circuit and pushed out in the morning. This included all the elements of the sea water section. The engine heat exchanger has not been removed, but there was healthy outflow on the sea water side. The flow increased significantly, when the I ran the engine at higher rpm.

I did the max rpm couple months ago on a weekend trip. There was no overheating at that time.

The coolant was replaced in 2018.

Ski in NC said:

If the HX is fouled on either side (or both), coolant at exit will be hot where it leads to circ pump suction..

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The pipe elbow, which connects to the engine at the thermostat, gets really hot. That is the spot, where the alarm switch sits, so it triggers the alarm. There is a 30-40F difference between the HX side of this elbow and the other end, at the thermostat connection. This elbow has a small hose section clamped in the middle, but nothing else. My guess is, there is little flow, or the thermostat does not open enough, and the coolant accumulates at this turn, making the elbow very hot.

I don't know the 3306, but I was able to find a link to a CAT 3306 water pump:

https://huace-parts.com/product/caterpillar-3306-water-pump-2w8002-2w-8002-for-sale/

It looks like the item you identified earlier in the thread and also looks to be gear driven. Possibly it's impeller has worn off or come loose on it's shaft?

Also keep in mind that even though you put a new thermostat on does not mean it's working correctly, a brand new part can be bad as well. Easy to test, drop it in a coffee cup full of boiling water and see if it opens.

Thinking about it some more, you say that the elbow gets hot on the side that's attached to the engine, but on the other side of the hose on the heat exchanger it's 30-40 degrees cooler. Sure sounds like the thermostat is not opening. The elbow bolted to the engine is probably getting hot just because it's bolted to the engine, and the heat exchanger is thermally isolated by the rubber hose, if the coolant was flowing it would seem like the elbow attached to it would heat up also. Does the heat exchanger heat up at all, or does it stay cool?

sbman said:

T Does the heat exchanger heat up at all, or does it stay cool?

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Yes it does heat up. You can on the photos that I have measured around 150-160F inside, sticking the gauge into the coolant. The housing of the exchanger is over 100F.
The elbow in question has a bit large diameter than the thermostat. Still, the flow should be sufficient enough to keep the elbow within normal temps. The alarm switch sits right next to it and it should trigger at 195F, which it does. It should not go that high. There is not enough coolant flow. Be it the thermostat or the water pump. I need test both. I have a quote for the pump around $190.

I am still waiting for the water pump and gasket kit. Hopefully I can do the swap and cleaning of the coolant section this weekend.

I took the boat out yesterday for a spin, but I did not get far. After about 20 idle speed, the temp went up to 180-190F. I disconnected the alarm switch and continued. It was stabile for a while, so I pushed the rpm higher. At 1000-1200 it was still around 200, but when I raised it to 1500 rpm the coolant boiled and the temp jumped to 240. I had to shut it down for a while. After restart, I moved very slowly back to my base. It just cannot handle higher rpm.

Not a good idea to run the engine under load until you get this sorted. Good way to trash the engine.

Ski in NC said:

Not a good idea to run the engine under load until you get this sorted. Good way to trash the engine.

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+1

Ignore those that are saying your gauges or temperature sensors are at fault until you fix problem. Years ago I worked at a place that had a dozen or so 3306s. The heads were very susceptible to cracking with minor overheats.

sunchaser said:

+1
Ignore those that are saying your gauges or temperature sensors are at fault until you fix problem. Years ago I worked at a place that had a dozen or so 3306s. The heads were very susceptible to cracking with minor overheats.

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I hope it did not happen this time. The run was less then a mile and lasted about 20 minutes. Most of the time I was moving with idle speed, with no overheating to extreme temps.
I wanted to see, if the overheating at 1500 rpm will happen underway, too? It happened before, while running in neutral, hooked to my buoy.
I watched the gauge closely and once the needle started to move up fast, I shut down the engine. Few minutes later I started it again, but ran it only on idle at 700 rpm and it cooled down to 180F and stayed there.

What is the best way to see, if there was any damage to the head?

The latest:

The new water pump has arrived, but it does not look like the perfect match. Perhaps, some of you can advice me, if this pump can still be mounted on my CAT? See photos.

As of the overheating; the existing water pump is the possible problem. There are pins and a center bolt is missing, as you can see on the photo. The gear would connect to the assembly, but not securely. Since this is the same gear, where the sea water pump is connected to, I suspect that the damaged raw water pump has done further brake down on the water pump, as well. When the engine is at low rpm, the flow is enough to cool, but as soon the rpm goes up, the gear starts spinning and the impeller cannot push enough coolant around. This is our theory.
Of course, the only way to prove it, if I have a functioning water pump. I will talk to the vendor on Monday, but this pump was sold as being compatible with my engine. Hopefully, it will be sorted out and a replacement pump will be coming?
I can see many variations on the web. Maybe there is a way to plumb this to the bottom of the expansion tank, but I cannot tell, because the space is very tight and hard to see anything there.
If any of you had the same dilemma and had to deal with mounting the water pump, please share your solution.

Something like that is what was seeming most likely.

New pump does not look compatible, just judging from photos.

May be able to source the pins and that center bolt and continue using old pump.

Could bolt and pins escape capture?

Are mating gear teeth looking ok?

Ski in NC said:

Could bolt and pins escape capture?

Are mating gear teeth looking ok?

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I think the bolt and pins were grinder to dust and were drained with the oil changes.

The teeth look ok.

Yes, I want to salvage this broken pump. Once I can find a replacement, I will send it out for rebuild. It will be a backup pump.

Pumps may be different for road engines and marine engines because of different cooling methods. Knowing Cat, you probably took out a second mortgage. eBay is a good place to look for parts. Another is:https://www.surplusman.com/
They buy and sell engines and parts. Lots of stuff, all US makes of commercial motors.

Lepke said:

Pumps may be different for road engines and marine engines because of different cooling methods. Knowing Cat, you probably took out a second mortgage. eBay is a good place to look for parts. Another is:https://www.surplusman.com/
They buy and sell engines and parts. Lots of stuff, all US makes of commercial motors.

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Thanks Lepke

Yes, parts are not cheap. I hope it will slow down a bit. I mean the spending. The only satisfaction I have with this issue is the learning. That is always valuable.

I went to the web site you recommended, but there is not much for 3306 engines.

I also did some digging about the pump mishap. The vendor was pretty sure that the pump I ordered was the right one, based on the serial number.
It turns out, CAT has changed the part number on the water pump, so it is very difficult to locate the right one.

Here is the line up:
CAT water pump old number / 3N-2850
Engine serial number / 66d24028 (4N9962 engine arrangement) Built as an industrial engine, but was converted to marine config.
CAT water pump NEW number / 172-7777 / Pump GP-Water side inlet
The vendor sent me pump # 2P662 / 172-7776, which corresponds with the pump you can see on CAT web site for 4N9962 engine arrangement. It is immediately visible that is a different pump. The center bolt for the gear ends outside and the inlet is at the bottom.
The pump I have (originally 3N-2850) can be found on the 6N-6294 engine arrangement only. It has the bolt inside, pins, side inlet, drain plug at the bottom, for marine configuration, turbo, aftercooler.
So, the whole thing is a mess.

In my parts book, I can narrow down the missing pins and bolt, which goes inside the gear. It should not be expensive. If that works, I could have a backup water pump.
Regardless, I do want to have a new and working water pump, even if it cost me.

Were there any remnants of the pins and bolt in the old pump and gear? If they failed there should be remnants trapped in the holes. If not, fair conclusion that they were not installed. If the mating surfaces are still in good shape, get pins and a bolt and install them. Fair chance the pin sizes and bolt are SAE standard dimensions so they need not be sourced through CAT. Though if CAT has them, that is the easiest way.

Get the engine back in service with old pump and then you can search for a new pump at your leisure.

Ski in NC said:

Were there any remnants of the pins and bolt in the old pump and gear? If they failed there should be remnants trapped in the holes. If not, fair conclusion that they were not installed. If the mating surfaces are still in good shape, get pins and a bolt and install them. Fair chance the pin sizes and bolt are SAE standard dimensions so they need not be sourced through CAT. Though if CAT has them, that is the easiest way.

Get the engine back in service with old pump and then you can search for a new pump at your leisure.

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Yes, that is my plan. I’ll try to find them in the next few days and install the old pump.

We could not see any pieces of the pins or the bold. I will look more in the bilge, but nothing was found, while I was pumping out the coolant from below.
Perhaps they were not installed, but that brings up a question; how was this pump running for the last 2 years, since I have the boat? I did run it at high rpm, all the time.
Puzzling questions.

FWIW Leo most circulating pumps have a metal impeller. If the bearings are OK and the bolt and pins are installed should be OK.

Didn't have anything left over from removing the other pump ??

Ski in NC said:

Were there any remnants of the pins and bolt in the old pump and gear? If they failed there should be remnants trapped in the holes. If not, fair conclusion that they were not installed. If the mating surfaces are still in good shape, get pins and a bolt and install them. Fair chance the pin sizes and bolt are SAE standard dimensions so they need not be sourced through CAT. Though if CAT has them, that is the easiest way.

Get the engine back in service with old pump and then you can search for a new pump at your leisure.

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It looks to me like the original pump has an internal spline to drive a second accessory on the opposite side of the gear case. If this accessory drive is not installed the pins are not needed, as the bearing retainer may only there to retain the bearing, not drive the splined output. The bolt coming out may have let the pump shaft to move forward and slip on the drive gear.

If this is the case the engine would have until the bolt came out, and a new bolt should fix it. Hopefully the bolt and its lock washer are comfortably and harmlessly lounging in the oil pan.

Solly said:

FWIW Leo most circulating pumps have a metal impeller. If the bearings are OK and the bolt and pins are installed should be OK.

Didn't have anything left over from removing the other pump ??

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Other pump? You mean the sea water pump? No. It was replaced and the oil was changed 2 times.