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Visitor

Re: CAT 3126B engines with diesel in coolant

Thank you, it turns out it was not the injectors but the oil coolers.  Seemed odd both failed at same time.  I ordered new coolers instead of rebuilt (close to same price) and of course the Cat mechanic installed rebuilt coolers but the oil is no longer in the coolant.  Thank you

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New member

Re: CAT 3126B engines with diesel in coolant

You boaties seem to have a similar problem to the school bus drivers.... Diesel in the coolant.   In my immediate area there are 3-4 of the 3126B engines that appear to have the same problem.   Our problem is perhaps a bit more urgent than yours, as we have kiddies sitting inside the bus while the diesel rots the heater hoses and leaks out pinholes.  The fumes from the diesel fuel/antifreeze mix becomes very strong, to the point of choking the kiddies and the bus driver which  forces it into an out-of-service condition.   In summer/warmer days you simply shut off the water supply to the heaters and open the windows. But now that its cold, heat comes on, the windows go up and the stink gets bad quick.

 

The answers that are supplied here have saved me from a really lousy Christmas, as I was just short of panic and about to buy a bus to run my route with...  Anywhere from $10k for really used to $120k new.  

 

My bus will be at the CAT dealer as soon as I can get it there Monday morning.  I'll let you know the results.

 

GJ

Contributor

Re: CAT 3126B engines with diesel in coolant

There's no way coolant and fuel can mix if the seals on the injectors are bad, the coolant/fuel seals are on the outside of the sleeves aganist the head.

 

I don't see how a change of injectorseals can fix a coolant/fuel mix problem, perhaps something moved just a tiny bit when the injectors was pulled/installed to make the leak seal.

New member

Re: CAT 3126B engines with diesel in coolant

The 3126B engines have been great, since I fixed the problem with the coolant. I've put plenty of hours on them, in all sorts of weather, and they have performed beautifully. Very reliable, no hassles. Hope that helps.

New member

Re: CAT 3126B engines with diesel in coolant

To all who have read this post and offered advice, I want to thank you for showing the interest and taking the time to help a fellow boatie out. I'm sorry for the delay in replying. I changed the injector SEALS only, since at the time I didn't have the correct tooling to change the sleeves, and thought it'd be worth a try, since lots of people here thought that alone might fix it. I've run the engines for more than 100 hours since changing the seals, and they work like a charm. The coolant looks as good as the other side now, and I've just serviced the engines and sent the fluids for SOS analysis to be sure, but I think that's done the trick.

I might mention though, that soon after changing the seals, I retested the coolant, and it still had diesel and some rusty brown discoloration in it, which threw me right off. After much angst, I eventually noticed that in particular on the Azimut, the Port engine coolant line (with the hassles) is connected to the hot water heater (freshwater circuit) on a recycling circuit, and the inlet tap to the heater was switched off, so no fluid was flushing through it, but little by little, the residual diesel and old coolant already in the heater core was trickling back into the fresh coolant via the outlet tubing!! I then had to dump the coolant (expensive!) again, flush the entire system with the tap open MANY times, then refill it and run it up. Since then, there have been no further problems, and we also have hot water from the taps when underway, without using electric power.

Once again, thanks to all for the good advice, and for helping fix the problem. This forum is great!!

Contributor

Re: CAT 3126B engines with diesel in coolant

hi tony

 

 In my opinion , the most probable cause for your problem is bad or damaged injector seals , since the injector sleeves on this type of engines is not like the copper sleeve on the meui engine and its harder and the chance to be cracked is very low. also in my opinion , the chance of having a crack in the cylinder head is low if the engine didnt overheat previously.

Visitor

Re: CAT 3126B engines with diesel in coolant

I have twin 3126 with 1,600 hours in a 51 foor 2001 Ocean Alexander, noticed both overflow reserve containers looked like oil filled or very dark through the plastic.  Sampled coolant in engine and overflow and was bright pink but then swabbed the walls of the reserve containers and rag came out black, smelled like oil (or diesel) with oil consistency.  Surprized both engines look exactly the same.  Cannot find any location where oil could mix with coolant unless the injectors issue is the source?  Has anyone solved this issue by replacing the injector sleeves?  Kim

Cat Dealer
Employee
Dealer

Re: CAT 3126B engines with diesel in coolant

Diesel in your coolant is coming from bad seals from your injector sleeves!

Ask your local dealer the replace the seals.

Contributor

Re: CAT 3126B engines with diesel in coolant

Fuel in coolant is almost 100% bad sleeves or seals.

 

Pull the injectors and replace the injector sleeves, it's a quick and easy job with the CAT tooling avaliable, should be able to do it in 3-4 hours easily.

Contributor

Re: CAT 3126B engines with diesel in coolant

Tony:

 

If the cobwebs aren't too thick on your post and you see this, then you will want to visit www.boatdiesel.com where your issue has most likely been discussed.

 

Paul