Replacing thermostats in my 3126 Cat.

[RCtime]

Any advice on replacing my thermostats on my 3126E Cat engine.
Im thinking about it after my local Cat. dealer quoted $525.00 plus parts.
Or is that about right. Replaced many of them on my car engines.

[autofish]

RCtime I did mine it was very easy so just go for it and save the $$$$

[JoeT]

I think $525 is a little high. I just had my coolant replaced with CAT ELC, which required flushing the system because my old coolant was not ELC. Replaced the thermostats at the same time. $448.11. That includes the coolant, thermostats and labor.
You should be able to change them yourself, though. Access is the hardest part.

[smlranger]

I did my own this past summer. I would not say it is 'easy,' but it ain't worth $525 IMO. If you have a north/south bed like mine, you will have to remove the bed platform to gain access, unless you are a magician. The most difficult part was getting the old gasket off the engine. I used a wood chisel to scrape it off.

Give your fan hub a shot of grease while you are in there. I also took the opportunity to clean the CAC and radiator while I had such good access.

[ernieh]

I changed mine recently and it was pretty much like smlranger said. I didn't need to change the coolant at the same time, so I drained it down to below the thermostat housing and then refilled to that level before installing the new thermostats.

That way I was able to top off only once.

[RCtime]

Im going to give it a go., the wood chisel for removing the gasket is a good idea.
I just had my coolant replaced last year and have an extra gallon left over, I understand you want to fill the housing to fill coolant over the thermostats, as coolant, not air makes them perform as they should.
My temp. gauge while driving fluctuates, reading normal, then temps drop, then come back to normal.,
I have had the coach 3 plus yrs now and I dont know if they have ever been changed.
Thanks for the replies.

[RKL]

If everything cooling wise is performing normal and the coolant has been changed per maintenance schedule, is it necessary to change the thermostats at certain mileage periods...thanks RKL

[wagonmaster2]

Originally Posted by RCtime

Any advice on replacing my thermostats on my 3126E Cat engine.
Im thinking about it after my local Cat. dealer quoted $525.00 plus parts.
Or is that about right. Replaced many of them on my car engines.

I have a feeling all Cat dealers are notoriously high on their labor on motor homes. Either they don't want to work on them in the first place or they see all MH owners as the pot of gold at the end of the rainbow. My Cat dealer charged me $450 for a 2 hour valve adjustment when most owners were getting it done for around $250-$295.

I replaced my thermostats a couple of years ago on a Cat C-7 and besides the work getting to the housing I had a terrible time getting the housing to separate from the engine to get to the thermostats. Cat claims they didn't use any kind of sealant on the gasket but I had to keep soaking the gasket around the housing with a rust spray and using a very thin putty knife. Everyone warns about being careful not to damage the metal so no danger of causing leaks. Understand there is a product available at parts stores made to soak gaskets loose with but wasn't aware of this at the time of my replacement.
Good luck with your job.

Wagonmaster2

[bdpreece]

If the cover won't come off don't try to drive something under it that might score the cover or the block. Try giving it a couple good smacks with a rubber mallet to break it loose.

[BZam]

Originally Posted by RCtime

Any advice on replacing my thermostats on my 3126E Cat engine.
Im thinking about it after my local Cat. dealer quoted $525.00 plus parts.
Or is that about right. Replaced many of them on my car engines.

This discussion caught my eye. Why replace them? Age? or different temp?

My 99 3126 performs great even in last trip across the 120 degree desert and over the Rockies.

Also, did not know there were two. Can someone explain this?

Bob

[wagonmaster2]

I guess the diesels have 2 thermostats to allow more coolant flow when they are open. The housing is sort of oblong instead of round to allow both to set side by side.

Cat recommends replacing them every three years. I always wondered why since I have a 10 year Jeep and an 19 year old Honda that have never had a thermostat changed. But then when my 2004 Cat C-7 started having some funny coolant temperatures a couple years ago I pulled the thermostats and one of them had come apart keeping it from neither completely closing nor opening entirely. The engine was taking forever to warm up on level highways and was overheating going over mountain passes. New thermostats fixed the problem, now it reaches full warm up temperature in 2-4 miles and only heats up 4-5 degrees more going over passes.

Wagonmaster2

[smlranger]

Originally Posted by RCtime

Im going to give it a go., the wood chisel for removing the gasket is a good idea.
I just had my coolant replaced last year and have an extra gallon left over, I understand you want to fill the housing to fill coolant over the thermostats, as coolant, not air makes them perform as they should.
My temp. gauge while driving fluctuates, reading normal, then temps drop, then come back to normal.,
I have had the coach 3 plus yrs now and I dont know if they have ever been changed.
Thanks for the replies.

I was able to remove the housing by tapping on it with a plastic hammer. Also, the gasket material was like concrete. I did an internet search on 'automotive gasket removal' and found a number of suggestions to soak the old material with carb cleaner, followed by careful scraping with a wood chisel. It worked. I drained a gallon of coolant off before removing the hose and housing.

[RKL]

SMLRanger...When you said you had to remove the bed platform did you mean the wooden board under the mattress and then the metal engine covers?...Also where are the thermostats located when looking down at the engine from the street side of the bed?...Are they located above or below the fan hub? thanks as usual....RKL

[smlranger]

Originally Posted by RKL

SMLRanger...When you said you had to remove the bed platform did you mean the wooden board under the mattress and then the metal engine covers?...Also where are the thermostats located when looking down at the engine from the street side of the bed?...Are they located above or below the fan hub? thanks as usual....RKL

I removed the mattress and the entire hinged bed platform. My T-stats are on the street side top of the engine at the very back...above the fan hub. Access is pretty good once the platform is removed. Mine had some of the large wire bundles in the way a bit.

Also, the 6 bolts holding the housing were pretty grundgy so I buffed them up and coated the threads with some anti-seize compound before reinstalling them.

[RKL]

smlranger...Gary thanks, exactly the information I was looking for....RKL

[RCtime]

Caterpillar 3126 Diesel engine in a motor home engine bay compartment. | Flickr - Photo Sharing!

I found this online photo of a 3126 Cat. inside a motorhome.
It appears to me the thermostat is located to the right of the cyl. head and left of the alternator and buried under some wire bundles??

I wish my bed folded up this much to expose the engine.

[cbeierl]

This is the access on my Vectra:

Normal Access (bed raised)


Full Access (bed removed)

[CWHTRAINS]

Would it be possible for some one to point out with an arrow on the pictures above where the thermostats are? I am trying to decide if replacement of them is something I want to do myself, but I do not know where exactly where they are. I have done all the other normal service, filters, etc. myself, and am ready to do a coolant change this spring.

[cbeierl]

The (faint) red circle in the upper right marks where I believe the thermostats are:

[CWHTRAINS]

Thanks Chris.