Cat 350 engine issue - false overheating?

runriver · 05-20-2018, 09:56 AM

Hello, my husband and I have a 05 Winnebago Journey, Cat 350 engine. We are having a weird problem with it. It acts like it is overheating, in that the gauge runs high (above mid mark, even at 50 mph), and will indicate that the engine is hot on the trip computer when the gauge goes above the 3/4 mark. The check engine light is on and off. We don't have an actual degrees read out. We are towing a full size pickup, and have been on really gentle grades, but have to truly climb to get home.

We have taken it to two shops to get the engine codes checked. Both said they could find nothing wrong, no error codes, and that it was not overheating.

We are traveling and trying to find a shop to take it to figure this out, but we are wondering if anyone else has had an issue like this.

Thank you.

Oldchinahand · 05-21-2018, 10:45 PM

Explore the tags beneath your post for some really good insight into your "issues".

Delete your rig description and insert ours and you have written a post that we would have written two years ago. Luckily, we finally turned to WW Williams here in Tucson. High praise on our part. They shared experienced suggestions, we followed through and (knock on wood) life is good.

Worn out trans fluid can contribute to over heating and intermittent engine warning lights. Trans may need drain, flush and fill. WW Williams also sliced open the filter to check for metal particles.

Oil and dirt deposits on your CAC and radiator will cut down their efficiency. Clean them. Engines of the age of our rigs often have crankcase breather tubes, "slobber tubes" that dump oily fumes forward of the engine fan, which then blows it and dust onto the CAC and radiator. You need to retrofit a method to capture those fumes.

Rodents love to nest between the CAC and radiator. In days, not weeks, they can build enormous nests, check for that.

Finally, although it is an automatic trans, when you are pulling long grades or steep hills, downshift to keep your RPMs up. For me that is in the 2500 - 2700 range.

I have an earlier post titled High temps, slobber tubes, rodents and kayaks, the describes - with pictures - how we solved our symptoms. As we seem to share those symptoms, hopefully our solutions will assist you.

runriver · 05-22-2018, 07:28 AM

Thank you so much for your reply! We are going to print it out and take it to the service person today. We knew about the radiator getting dirty and have had it cleaned twice, but aren't completely sure how thoroughly that was done. We have not yet learned to do it ourselves.

FIRE UP · 05-23-2018, 10:31 PM

runriver,
Much of the info you're received is pretty good. I will add a bit. 1. You have the CAT C-7 350HP version. Yes, it has a "blow-by" tube. The blow-by tube is a crank case ventilation system. In that, there are internal pressures developed inside the engine while running. That pressure has to go somewhere. It is directed to the atmosphere, via this Blow-by tube. The problem with it is two-fold.

A. When the coach/chassis was built, the exit point for that tube was just below the centerline (vertical) of the engine.
B. Due to confusion, assembly line characteristics, poor coordination between design folks and manufacturing and more, the actual amount of engine oil to be inserted, either when new or, when periodic engine service was/is performed, has been in question for a while.

It has been narrowed down to two answers.

1. Whether or not, any particular version of a C-7 (300, 330 and 350 HP) has a steel or, aluminum oil pan. Those two oil pans are DIFFERENT CAPACITIES.
2. Since apparently some of the info from CAT is either incomplete or simply inaccurate, (based on phone calls to and from Hot lines) it has been determined that, if you have a steel oil pan (about 99.999% of the motorhome chassis with the C-7 do), your maximum oil capacity or, the maximum that is to be added to the engine after an oil change is,

NINETEEN QUARTS, TOTAL, INCLUDING PREFILLING THE FILTER!!

And this is where the blow-by tube comes into play, more than other times. By having too much oil in the crankcase, the execessive oil get's sloshed around foams. When that happens, there's more oil vapors inside that engine block than there is supposed to be. And, because there's pressure inside that engine when it's operating, the pressure AND THE VAPORS exit out the blow-by tube.

Now, if that blowby tube is still exiting at the vertical centerline of the engine, next to the oil pan, those vapors or, a form of an "oil mist", get's sucked up by the engine fan and, where does it go? It get's SPRAYED all over the CAC (Charge air cooler)(turbo air cooler) both mean the same thing. And it also get's sprayed onto the fins of the radiator. NOT GOOD!

So, when that happens, those fins are now oily. Ok, you're traveling down the road and, your engine fan is doing its job of PUSHING gobs and gobs of air through both those units, trying to keep both of those components cool. But, that engine fan is also SUCKING UP every particle of dust, debris, fiber, leaves, BUGS (dead and alive), paper and plastic bags and a whole lot more.

And, it then jettisons all of what it picks up and, where is it sent, TO THE OILY FINS of both components. Well, that's not a good situation at all. Because, those fins can only take so much, before they start to seal up, all the passages of air, THAT IS SUPPOSED TO BE COOLING THEM. The more those fins clog up, the less air get's to pass through both of them and, since there's no cooling air, the coolant doesn't get to be cooled, NOT GOOD!

So, what's the cure for all this?
1. The blow-by tube exit point needs to be lengthened to a position where it exits outside the back of the coach.
2. And this is very important, when and during an oil change, make darn sure that ONLY 19 QUARTS OF OIL is inserted in the engine, including what's pre-filled in the filter.

Now, is all this the reason for your potential "overheating" issue, can't guarantee anything. It is the cause of many, many over heating Winnes and Itascas with both the C-7s and the predesors, the 3126.

Here's another problem. CLEANING those rear radiators and CACs while their still in the coach, ACCURATELY AND EFFICIENTLY, is darn near impossible in most cases. Access to ALL the fin area is the really, really tuff part. Some folks have developed certain methods for obtaining a somewhat clog-free radiator and CAC. But, those are rare. Does your coach need some attention in this area/situation, well, only you can tell.

I have pulled my radiator out of our coach TWICE for various reasons and, cI can tell you, no matter how well you think you do on periodic cleaning, there's still a considerable amount of debris/dust/leaves/dirt/animals etc. that can get lodged in the corners and other areas of the fins, that can't get direct cleaning.

Anyway, those are some of the potential reasons for your over heating. I don't like long, drawn out posts, like I just wrote but, sometimes it's necessary so that a person or, persons can be accurately informed. Hope this helps some.
Scott

Oldchinahand · 05-24-2018, 12:48 AM

Great detailed explanation of the drawbacks inherent with the crankcase breather tube and ensuring proper oil fill at change.

I've seen a number of "fixes", most of which included some sort of container to condense and capture the oil fumes. In our case, we led 3/4" CPVC from the tube aft past the radiator. Helped the CAC & radiator, but didn't help our dinghy. Addition of an empty plastic mayo jar filled with steel wool solved that.

We've removed our CAC & radiator once for deep cleaning. Expensive to have done, a job for a full grown man (or three) if DIY. Another solution many of us have chosen is to install a cleaning access in the radiator shroud. A specific coach may not lend itself to that, however. And still a full days work to utilize.

Pictures in the link

http://www.winnieowners.com/forums/f...ks-349987.html

Fair Winds and Following Seas!

runriver · 05-26-2018, 09:34 PM

Fire Up, thank you for the explanation. I had read that there was a challenge related to keeping the radiator clean, but not fully understood it previously. I think I'm beginning to "get it," and that this will make it easier to talk to the shop people.

My husband and I have been thinking that we should learn to clean the radiator, but its really unlikely that we will be able to do anything as extensive as remove the radiator.

We are still waiting to hear from the shop where ti is currently if they think it is truly overheating or if there's a malfunction with the gauge or sensor. However, it sounds like even if that's the case, we really need to figure out how to tend to the radiator.

Thank you!

Cloudrnnr · 06-02-2018, 09:06 PM

Ditto what everyone else said about cleaning the CAC and radiator (especially the space between them) and I'll reiterate what Terry said about keeping the RPM up. I had not given my wife adequate instructions on pulling up a grade during one of her early turns at the wheel in our 2004 36G She left the cruise engaged, with our Jeep in tow, and a 95F day headed up Satus Pass in Washington. We got the overheat warning just as we reached the summit. No matter what the grade, we've never had a high temp as long as we gear down to keep the RPMs above 1700, and slowed to a speed that could accomplish that. The 350 is not underpowered, but it isn't a huge performer either.

runriver · 06-03-2018, 09:46 AM

Cloudrnnr, can you say more about keeping the rpms up? My husband and I have had this ongoing debate about gearing down on a uphill grade. He typically will downshift to 5, I am more inclined to let the transmission make its own choices. Would you manually downshift, even lower than 5? Thank you!

runriver · 06-03-2018, 09:50 AM

The shop has recommended that we replace the radiator, and all the other parts and pieces (water pump, fan, thermostat), while its all apart. They tried steam cleaning the radiator, and said it was still blocked. Apparently we have been overheating, not just getting false information.

We asked them about lengthening the tube, but that was not something with which they were familiar. Is that something we can do after the fact, or should we really push them to do it while its all apart?

Our goal now is going to have to be how to keep the radiator clean! We drive about 30-40k/year so there is a lot of time when the engine is running.

Cloudrnnr · 06-03-2018, 10:19 AM

We downshift manually. The Allison will let the RPM get lower than we would like before downshifting. If I recall correctly, best cooling is 2000+ rpm under load, while best torque is around 1700. To keep the temps down, we sacrifice a little of the peak torque for the cooling capability. Pulling the RPM down seems to spike the temp much faster. I'm not an expert on the C7, but this seems to be working for us.

As for your shop's recommendations, with that kind of expense, I'd be inclined to ask for a second opinion if the coach isn't already pulled apart. A radiator replacement is usually only necessary if leaking, or there has been pretty heavy damage from neglect. I just removed the radiator and CAC, cleaned them, did the waterpump, thermostats, belts + tensioner, pulley bearings, fan hub, and hoses as part of my own 100,000 mile maintenance. I don't really want to know what a shop would have charged! Extending the "slobber tube" (crankcase vent tube) is a pretty simple job, not sure why they are giving you shrug. It can be done any time, but with a clean radiator, the sooner the better to prevent buildup. As FireUp passed along, getting the oil amount is critical. You can call Freightliner with you VIN and they will confirm the correct oil capacity. On our 36G, the dipstick was no where close to correctly marked. Filling to the "add" mark means you will have a black coated tow.

Where are you guys located, currently?

runriver · 06-03-2018, 11:44 AM

Cloudrnnr,

I think the ship has sailed on this repair. We work from our coach, so downtime creates some significant issues for us. We live in Upstate NY, near Syracuse, the coach is currently in Northern VA. That was about as far north as we were willing to take it, before we had to start some real climbs up I81. Our usual shop had also told us previously that if they were to pull the radiator to clean it, they would recommend just replacing it.

What you did with pulling the radiator, etc. is well beyond us from a mechanical standpoint.

Thanks to everyone's notes on the amount of oil; I actually have no idea what the shop has been putting in, so we will pay attention to that.

Cloudrnnr · 06-03-2018, 12:18 PM

The oil thing requires close monitoring of the shops doing the work. The first time we took the coach into a CAT dealer/service location, they put in 28 qts!!! That happens to be the originally published capacity for a C7 with a deep sump oil pan, but that is not what our coach has. The next shop filled up to the "full" mark, a total of 24qts. After lots and lots of steam cleaning on our TOAD, I finally got smart and began to monitor what we put in after calling Freightliner to confirm. Still sketchy on shops--no one wants to fill below the marks on the dipstick--so now I just change it myself. I still need a new dipstick, as mine is too short to really be usable, even with re-marking, but for now I know exactly where 19qts is on the stick, and just monitor it closely.

Oldchinahand · 06-04-2018, 10:34 PM

Can't help myself runriver. Going to jump back into this to expand on my previous comments.

No sarcasm -- I am in awe of cloudrnnr's wherewithal to remove his own radiator and clean it. It doesn't get any better than a good boiling out or sonic cleaning.

But the CAC and radiator can be cleaned very well in situ, with a few modifications taking a couple of hours, using simple tools you likely carry in your toolbox. Follow this link http://www.winnieowners.com/forums/f...ks-349987.html

And as cloudrnnr alludes, unless you change your own oil, you will always be plagued by excess oil and vapors being deposited on your dinghy, radiator, etc. Here are a few pics demonstrating a simple method of leading the crankcase breather tube aft of the radiator. Also, a simple catch container made from an empty mayo jar.

Fair Winds and Following Seas