Why do intercoolers on my MAN engines need cleaning every 2 years?

[Jonmendez]

You can rig a simple Rydelyme flush through on the sea water side, on my AD41's we take the outlet pipe off the seawater pump and connect it to a pumped supply (bucket with sucking pumps in it) of Rydelyme.This then pumps through the oil cooler, intercooler, heat exchanger, gearbox oil cooler then back to the bucket. We run it each winter for a couple of hours. The Rydelyme goes a disgusting colour and dissolves all the scum in the system. I also take out the intercooler matrix every couple of years and leave it in a bucket of Gunk overnight to remove the oil and ****. Seems to work well. You have to be careful though as the intercoolers are almost 2k a pop from VP and fairly easy to damage the internals.

 

[BartW]

Hi Mike, I’m late to this thread, and you’ve probably had some usefull advise above, and or made your conclusions,
Here is my limited experience;

2 years ago, while talking with MAN people on their stand at Mets
about a preventive inspection on my old engines
apart from the normal maintenance, oil, filters, belts, ….
they recommended to inspect the heat exchanger every now and then.
Also the injectors need regular inspection or rebuild,
They didn’t mention about a vibration damper 

after 2 seasons of using our boat with MAN engines we opened the intercoolers, and heat exchangers for inspection, (we ordered the new sealing’s in advance)
and noticed that all were perfectly clean.
we also noticed that the paint on the screws on one engines where never untightened,
the paint looked perfectly intact, so they were probably never opened before (?)

I assume that there can exist situations that make the intercooler, or the raw water pipes dirty as explained by the specialists here above.

Now just a few months ago,
when they opened the broken engine,
again the intercooler and heat exchangers were perfectly clean,

Regarding the temp difference that your skipper noticed,
there could be many reasons for that,
Such as slightly different specs on the thermostats,
or Issue with one of the water Cooling cirquits / pumps,
or oil cirquits, etc etc,

OR even navigating with different rpm on both engines can create a temp difference,
at least on my setup, perhaps less on more modern engines
And that is perfectly feasible with a non-experienced skipper on your boat (?)

So based on my experience I wouldn’t worry about a dirty intercooler, as long there is no abnormal smoke…

 

[Hardmy]

How many hours for doing them?

Sorry for being off topic, since it relates my CAT 3208TA's (425 hp). I had a discussion with the mechanic in Monopoli. He thought it was not necessary to do the heat exchangers / intercoolers now.

... I was a convert to the fitment of EGT (Exhaust Gas Temperature) gauges years ago. Any increase in EGT is indicator that CAC is becoming fouled...

So that's exactly what I did for obtaining some more comfort, those things are being fitted in the coming 2 weeks:

However I am still considering to insist and ask him to check exchangers / intercoolers as well as clean the exhaust riser / water mixer.

Any idea what this represents in terms of hours of work?

 

[BartW]

nice touch Hardmy,

I have one of these infra red temp guns in the engineroom,
and I compare temps on different spots on both engines on a regular base,


re checking the intercooler,
we now have a bore camera onboard, (<100 euro iirc)
not sure if there is a opening through which you could have a look inside

 

[MYAG]

Hi MYAG, it's listed in my manual under the A1 service schedule required every 2 years and btw it includes the heat exchanger too

Mike, I have just looked at my copy of the MAN service book on board, The D28 "classic" series engines do indeed have a 2yr interval for cleaning the charge air cooler listed under A1 along with the charge air pipes/turbocharger and heat exchanger, but as LS1 and BartW have suggested this might be overkill and it seems that MAN might be agreeing with them cos the "new generation" engines (2010 onwards) have the requirement pushed out to 4yrs. I will be opening mine up in May for the first time in 4 years, will let you know what I find but I guess nothing as the T&P's have always suggested.

 

[Deleted User YDKXO]

Now just a few months ago,
when they opened the broken engine,
again the intercooler and heat exchangers were perfectly clean,

Regarding the temp difference that your skipper noticed,
there could be many reasons for that,
Such as slightly different specs on the thermostats,
or Issue with one of the water Cooling cirquits / pumps,
or oil cirquits, etc etc,

OR even navigating with different rpm on both engines can create a temp difference,
at least on my setup, perhaps less on more modern engines
And that is perfectly feasible with a non-experienced skipper on your boat (?)

So based on my experience I wouldn’t worry about a dirty intercooler, as long there is no abnormal smoke…

Like your engines, Bart, it doesn't look like the paint on any of the bolts holding the intercoolers or the heat exchangers on my engines has been touched so just for my own peace of mind I'm having them opened up for inspection and cleaning. I always change the water pump impellors every year anyway. As you say, I take the information that the skipper has given with a little bit of a 'pinch of salt' since he is unfamilar with the boat. However, there is one other factor in this. The boat is currently still under warranty from San Lorenzo until the end of March so I have raised the issue with the yard and San Lorenzo now just in case there is actually a problem.

 

[Deleted User YDKXO]

Sorry for being off topic, since it relates my CAT 3208TA's (425 hp). I had a discussion with the mechanic in Monopoli. He thought it was not necessary to do the heat exchangers / intercoolers now.

However I am still considering to insist and ask him to check exchangers / intercoolers as well as clean the exhaust riser / water mixer.

Any idea what this represents in terms of hours of work?

Hardmy, one of my previous boats had Cat 3208TA engines in it and I cleaned the heat exchangers at about 800 hrs/7yrs with Rydlyme descaler. The Rydlyme appeared to remove quite a lot of debris but actually I found that there was no difference in the coolant temperature afterwards compared to before so on that basis, it wasn't necessary! But IMHO for peace of mind and if you think the yard is competent, why not have it done?

Regarding your new exhaust gas temp sensor, is it really fitted with plastic cable ties? How will the cable ties stand up to the high temperature of the exhaust pipe?

 

[Hurricane]

I'm late to this thread.
I'be been concerned for a while about this problem and, on a number of occasions at boat show, I've asked the sales engineers at MTU.
They have always been a bit mystified by the question, saying that they have never heard of anything like this.
Having said that, our heat exchangers are made from titanium and don't even have any anodes in the water circuit.
I've even questioned the gearbox coolers with similar response.

I've (kind of) made my mind up that at 1000 hours, I'm going to get a full service and do some un-necessary servicing.
Heat exchangers is on the list for un-necessary servicing.

It would be interesting to hear what the experts on here think.

 

[jfm]

Sorry for being off topic, since it relates my CAT 3208TA's (425 hp). I had a discussion with the mechanic in Monopoli. He thought it was not necessary to do the heat exchangers / intercoolers now.



So that's exactly what I did for obtaining some more comfort, those things are being fitted in the coming 2 weeks:

However I am still considering to insist and ask him to check exchangers / intercoolers as well as clean the exhaust riser / water mixer.

Any idea what this represents in terms of hours of work?

Hardmy, I don't want to rain on your parade but that EGT set up is a waste of time imho. What you want for diagnostic purposes is EGT before the spent cooling water is injected, but your system is measuring it after. Therefore the reading you get will be a blend of the engine's EGT diluted by the cooling water flow, and the reading will be more a function of the raw water flow rate than of what is happening with the engine. The only rational benefit of measuring EGT after the water is injected is to get an alarm when the water flow fails, and EGT measurement for that alerting purpose is an excellent technique. however, it requires a sensor inside the exhaust pipe not cable tied to the outside, because cable tying to the outside is adding perhaps 30 seconds of delay to what would otherwise be an instant alarm. As a say, I'm sorry to be raining on your parade but I'm saying it as I see it

 

[jfm]

LOL, funny you should ask that M, 'cause not only I'm sure it isn't FL original fit (and neither I've ever seen that as standard fitting on any other boat, for that matter), but the idea was firstly debated, back in 2010, here in the forum: http://www.ybw.com/forums/showthread.php?237755
And as you can see if you just read my OP, it was inspired by something I discussed with Mr.A, the guy you are now in contact with at the yard.

That said, chapeaux to jfm for actually implementing the idea, and shame on my laziness for not having done anything yet!

Yup Deleted User, that is an -after delivery mod as MapisM says. Intellectual property rights in the idea go to MapisM :encouragement:. (MapisM, you are a wizard at finding/linking old threads!)

Last week in the shipyard we had a lack of shorepower for a while and needed 230v, so I connected the hose and ran the generator for a few hours. It was perfectly fine - all temps normal. The spent water drained out under the hull and ran into a drain in the yard. Perfect! The neighbouring boats all stranded on the hard with no 230v were very jealous

 

[Hardmy]

Hardmy, one of my previous boats had Cat 3208TA engines in it and I cleaned the heat exchangers at about 800 hrs/7yrs with Rydlyme descaler. The Rydlyme appeared to remove quite a lot of debris but actually I found that there was no difference in the coolant temperature afterwards compared to before so on that basis, it wasn't necessary! But IMHO for peace of mind and if you think the yard is competent, why not have it done?

Regarding your new exhaust gas temp sensor, is it really fitted with plastic cable ties? How will the cable ties stand up to the high temperature of the exhaust pipe?

Thanks for your advice Deleted User, will check with the yard. Especially regarding the plastic cable tie, this cannot be.

Hardmy, I don't want to rain on your parade but that EGT set up is a waste of time imho. What you want for diagnostic purposes is EGT before the spent cooling water is injected, but your system is measuring it after. Therefore the reading you get will be a blend of the engine's EGT diluted by the cooling water flow, and the reading will be more a function of the raw water flow rate than of what is happening with the engine. The only rational benefit of measuring EGT after the water is injected is to get an alarm when the water flow fails, and EGT measurement for that alerting purpose is an excellent technique. however, it requires a sensor inside the exhaust pipe not cable tied to the outside, because cable tying to the outside is adding perhaps 30 seconds of delay to what would otherwise be an instant alarm. As a say, I'm sorry to be raining on your parade but I'm saying it as I see it

Also to you jfm, thanks for your valuable input. The primary goal of this sensor is to alarm me if I have an impeller problem or a blocked raw water intake. To be honest, I didn’t consider that there may be such a delay. However I do hope, it will at least help me to prevent capital damage in case of cooling disruption. Are there devices I could fit for measuring EGT before the water mixer (as you suggested) for such an old engine setup than mine?

 

[jfm]

Also to you jfm, thanks for your valuable input. The primary goal of this sensor is to alarm me if I have an impeller problem or a blocked raw water intake. To be honest, I didn’t consider that there may be such a delay. However I do hope, it will at least help me to prevent capital damage in case of cooling disruption. Are there devices I could fit for measuring EGT before the water mixer (as you suggested) for such an old engine setup than mine?

OK if you only want it as a raw water alarm, not as an EGT monitor to give you the precise data Latestarter and others refer to, then good stuff. A downstream EGT is imho by far the best way to get an alarm for pump failure. You can buy them where the probe goes through a fitting so it is inside the exhaust duct, and then the alarm is instant, like 1-2 seconds delay. The delay by having it outside depends on the properties of the material the duct is made from, but it's surely going to be say 30 seconds so why go there? Your exhausts might already have a boss for fitting an alarm probe, or you might have to fit a boss. Here's an example kit (which is OEM fitted on many UK boats, including mine)and it comes with parts to allow you to drill the rubber exhaust hose and fit the probe http://www.dekamarine.com/deka/media/halyard/catalogue/5. Exhaust Alert System.pdf

 

[MapisM]

The primary goal of this sensor is to alarm me if I have an impeller problem or a blocked raw water intake.

For this purpose, temperature sensors - wherever installed - are bound to be delayed to some degree.
The only VERY effective way to control that, and it's in fact a standard installation in those cases where a problem with raw water cooling is more likely to happen (namely, speedboats with water pickup on the outdrive nose), is a raw water PRESSURE sensor.
With an exploded impeller, a plastic bag on the intake, etc., the raw water pressure falls instantly to zero, well before anything happens to the engine/exhaust temperature.
I always wondered why such reasonably simple sensor is very rarely installed in "normal" boats...

 

[Robg71]

Hi, hope you have no issues with you CAC, after buying a large industrial ultrasonic bath, I opened mine up to find they were utterly stinking, blocked.
I would be under no illusion that yours would be anything like, but be aware its an issue with any heat exchanger.
We have plate style LT cooling water at work that get done every six months for example. Inside these we have mussels growing and all sorts.

 

[jfm]

For this purpose, temperature sensors - wherever installed - are bound to be delayed to some degree.
The only VERY effective way to control that, and it's in fact a standard installation in those cases where a problem with raw water cooling is more likely to happen (namely, speedboats with water pickup on the outdrive nose), is a raw water PRESSURE sensor.
With an exploded impeller, a plastic bag on the intake, etc., the raw water pressure falls instantly to zero, well before anything happens to the engine/exhaust temperature.
I always wondered why such reasonably simple sensor is very rarely installed in "normal" boats...

MapisM, the temp sensor inside a diesel engine's cooled exhaust will sense the problem in something like a second or two. When that plastic bag covers the intake the downstream EGT rises from say 100 degrees to 400+ that fast. The alarms is to all intents and purposes instant. Thus, it is on a par with a pressure sensor and a flow sensor imho as regards speed. The disadvantage of a pressure sensor compared with downstream EGT is that the pressure sensor cannot generally detect problems downstream of itself, eg a split hose just upstream of the exhaust elbow which is a potential fire-causing failure. So as ever it is a question of compromises and horses for courses, but imho downstream EGT sensor is the best system for a leisure boater

 

[MapisM]

Well, I actually suggested that to Hardmy who said that an impeller problem or a blocked raw water intake were his concerns.
Which in my experience are the most common problems anyhow, and effectively addressed by a pressure sensor.

But I see your point of course, and I don't disagree.
Just one further thought, how sensible do you think a downstream EGT would be in case of a partial obstruction in the raw water flow?
It happened to me once on my current boat (some floating garbage, which got stuck in the water pick-up but not enough to close all of it), and the engine involved had no noticeable temp increase (I'm talking of cooling liquid - I don't have an EGT sensor).
Also, the water discharge astern (yeah, no u/w exhaust either! ), seemed good enough, at first sight.
Funnily, the only alarm that went off was the one of the stabs oil circuit, whose cooler is downstream of the engine heat exchanger and was obviously getting warmer water due to the lower flow.
In fact, initially I didn't even think of a problem in the raw water flow, and eventually decided have a look under the hull mostly because after staying for a while in the warm e/r, I was wishing to jump in the water anyhow...

But I digress.
Back to the point, I always thought that with a water pressure sensor the change would have been noticeable.
Do you think the EGT sensor would have been equally effective?
Genuine question, mind - not meant to prove that either alternative is better.
In fact, also my assumption that the pressure reduction would have been noticeable is just an educated guess...

 

[jfm]

Hi MapisM. All agreed there. There are advantages/disadvantages to both so there is no clear winner, but on my personal scorecard the fact EGT measures at the END of the water run not mid way is quite a big deal, because there are plenty of failure points downstream in the raw water circuit.

I don't think anyone can say that a pressure sensor or temp sensor would be better or worse with partial blockage. The catch is that both are installed as binary on/off alarms, so it depends entirely where the trigger point is set, and whether the partial blockage hits the trigger setting or not. TBH, I do not know where the trigger point is set with EGT systems but I bet it is well above "normal running" to avoid false alarms in high load running, so a partial blockage might not trip the alarm. I guess the same with raw water pressure alarms, because you do not want the low pressure alarm to trigger at idle

In a perfect world I suppose you would have a guage readout of pressure/temp, AND a bleeper alarm, and 10 seconds of google led me to this very fine device http://www.maretron.com/products/fpm100.php

This little baby is about €300, can be plugged in with minimal cabling (I have N2k backbone in e/room) and has six channels so one unit will cover (say) both gensets, both engines, the hydraulics (I have a separate cooling water loop with separate pump for the hydraulics) and the airco raw water. For a boating device, this is quite bargain! (Still gotta buy the transducers of course). I'm busy with a lot of other maretron stuff right now but I might install this next time. BTW I think most engines have lots of screwed-in plugs in the raw water cooling circuit (some for anondes, some just plugged holes) so finding a place to screw in the transducer will be easy I bet.

Very OT, but I gotta say I love maretron stuff. I've installed a lot this winter.

 

[Portofino]

If the raw water cooling was interrupted -catastrophically -for what ever reason ,( impeller damage ,blocked inlet being top of list )
Then for the EGT to rise - bearing in mind the engine is happly puffing away with the same fuel set by the throttle ,
the water temp guage will start to rise first by lack of water round the block and head - things will start to overheat
The hotter head will then lead to increase EGT .Upstream
That's why we have a water temp guage as basic info .
Downstream EGT,s like Hardmy ,s are designed to tell you that your plastic or other exhaust pipe is about to melt -cos there's no water ,
But I suspect your water temp will start rising first ( which you may see or be alarmed ) before cos all thing s being equal
The head has to get hot first for the EGT to increase .upstream

I think the Germans- MAN know what to monitor 16 engine parameter s screen shows groups of 4
Ours is EGT from the manifold upstream of the riser so if it's trending slowly up and all the others are not it tells us ---
A- its hot in the engine room today ( outside temp 95 oC in August SoF)
Or B - the fins in the CAC are fouled / fouling ?

I suspect catastrophic raw water failure will be a sudden water temp rise + alarms first B4 EGT is noticed ?

We also have gearbox oil pressure and temp and of course engine temp / pressure
So if water temp for me 82 oC and gearbox oil temp ,and engine oil temp ( oil coolers ) start to gradually climb
Then it's the tubes -ie time for a Rydlime flush .
Or ---
That's when you dicide to open it up -when the engine tells you .

 

[jfm]

your water temp will start rising first.. .

thats not correct. With a total raw water flow failure the downstream egt temp will rise a couple of hundred degrees C within literally a couple of seconds. Downstream egt sensors (along with a raw water pressure/flow alarm) are the only sensible way to get a fast alarm. If you wait to see the jacket water temp rise you've already got your plastic/rubber exhaust system nicely on fire and your holiday is over.

Ref MAN, engine manufacturers don't include downstream egt in their instrumentation because they don't make exhaust systems.

 

[Robg71]

Technically i think you have a chicken and egg,." irrelevant really if the water or cylinder head is warmed half a tenth of a degree before the egt probe goes berserk. Far much more metal and coolant to dissipate heat before any real change to a coolant gauge, whilst exhaust is already on fire. Lack of items in the exhaust to dissipate that heat means it will be the first to squeek an alarm.....