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Hurth Transmission Oil [E35-3]

Hagar2sail

Member III
Blogs Author
So I am to be condemned for the fact that we have owned our boat for three seasons, and I have not changed the transmission oil. This is due to two facts:

1. The amount of boat yoga to get to our drain plug is daunting, in fact I am not sure if I can reach it without taking the heat exchanger off the engine. The hot water tank prevents me from getting to it from the aft lazarette.

2. I can’t seem to find out what oil I should be putting into this thing, and have read about Hurth HBW failures on this forum and am terrified of destroying ours with the wrong oil. Right now it just works, and that is good...

I see in the manual it says “Type A” transmission fluid. I have discussed this with basically every car parts place in the area, several who told me I was nuts, there was no such thing, one who told me to use the GM “anything” fluid, and one who finally relented, looked in his computer, found “Type A”, grunted about the fact that that was the darndest thing, and then said the didn’t have any in stock in the whole country, and it must have been replaced with something, but he couldn’t tell me what. So what type of fluid are people running here in their Hurth transmissions? I figured I need to relent at this point, and actually give the transmission some TLC.
 

Joliba

1988 E38-200 Contributing Member
I ran into the exact same issues when we got our boat in 2008. After consulting with some trusted mechanics, I have used ATF “automatic transmission fluid” readily available at car parts stores for my old Hurth transmission. It has caused me no problems.
Concerning the inaccessible drain, there is another solution. I remove the fill cap (that is also a dipstick) and perform the entire exchange through the top. I use a 60cc medical syringe with a short length of narrow clear tubing to draw out the old fluid. This easily reaches the bottom of the case where the drain is located. If the old fluid is contaminated, it’s a good idea to suck out what you first put in and then fill it once or twice more with fresh transmission fluid to flush the sump. One small container of the fluid is enough for several years of exchanges.
Good luck!
Mike Jacker
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
I recall that Hurth model 50 holds about 10 oz. That's not very much. As Mike points out you can suck out the old and input the new via the top plug (fill plug with the dip stick attached). For that last number of years with that transmission I was using synthetic ATF, I should note. Spending a bit more for the oil seemed like an idea to treat that transmission a bit better - like giving it a 'treat' for good behavior.
:)

I used to take the bolts out that held the heat exchanger bracket in place and move it an inch or so out of the way. When doing this be careful that the hose to the exhaust manifold does not loosen.
 

Geoff W.

Makes Up For It With Enthusiasm
Blogs Author
I used ATF when I recently did this job on my own. It was much easier with the heat exchanger off, but not impossible with it on. Just takes some boat yoga and extensions for the socket wrenches.

Be sure you get all the old stuff out. It was hard to tell how much oil was in there from the dipstick -- I found it easier to know the trans was at 0, and then pour the correct amount from the quart of new fluid.

My first go, I had too much fluid in there, and the trans was sluggish and wouldn't engage consistently. Made for an exciting round trip to the pump-out dock.
 

Tom Metzger

Sustaining Partner
For that last number of years with that transmission I was using synthetic ATF, I should note. Spending a bit more for the oil seemed like an idea to treat that transmission a bit better - like giving it a 'treat' for good behavior.

Being an old transmission, a Hurth HBW-50, I thought it best to check before putting synthetic ATF into it. The Universal distributor Hansen Marine Engineering service people told me that the synthetic ATF is too slippery and should be avoided. A local mechanic told me the same thing. I returned the synthetic and got the recommended Dexron III non-synthetic ATF. I saved .003 boat bucks.

Note that Loren after putting synthetic ATF into his tranny had to replace the whole engine/tranny. Not saying this was the reason, but... :>)
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Caution is always a good idea.... OTOH, one of the many reasons we changed to more modern engine and transmission was the mass of anecdotal evidence that nearly anything, including the phases of the moon, can cause a Hurth 50 to fail. :(
 

Hagar2sail

Member III
Blogs Author
Thanks for all the replies. I guess the specific question I missed asking was are you guys finding just something that says “ATF” or using specifically “mercron”, “dextron III”,”dextron IV” etc. I feel like when I looked there was always a defined spec on the bottle. I’m mostly concerned because from my reading around on car sites “Type A” became dextron and had friction modifiers, while “Type F” became mercron and didn’t have friction modifiers, but now it is confusing as there are multiple modern versions products that say they cover both, and how could they? One should have a different friction coefficient than the other. And then of course the million dollar question....does it matter for our Hurth transmissions.
 

Hagar2sail

Member III
Blogs Author
Caution is always a good idea.... OTOH, one of the many reasons we changed to more modern engine and transmission was the mass of anecdotal evidence that nearly anything, including the phases of the moon, can cause a Hurth 50 to fail. :(
Haha, this is probably the truth
 

Hagar2sail

Member III
Blogs Author
Being an old transmission, a Hurth HBW-50, I thought it best to check before putting synthetic ATF into it. The Universal distributor Hansen Marine Engineering service people told me that the synthetic ATF is too slippery and should be avoided. A local mechanic told me the same thing. I returned the synthetic and got the recommended Dexron III non-synthetic ATF. I saved .003 boat bucks.

Note that Loren after putting synthetic ATF into his tranny had to replace the whole engine/tranny. Not saying this was the reason, but... :>)
Thanks Tom. I was circling the drain on a dextron III as my preferred replacement, sounds like the best bet. How many years you been running on it?
 

Tom Metzger

Sustaining Partner
Thanks Tom. I was circling the drain on a dextron III as my preferred replacement, sounds like the best bet. How many years you been running on it?
24 years, but being a lake sailor I don't put many hours on the engine, particularly the last couple of years when the boat has been mostly a camp. Prior to that mostly used the engine just long enough to bring it up to full temperature before and after the days trip. I would rather sail slowly than listen to the engine. On Lk Champlain destinations can vary by wind strength, especially when retired.
 

mordust

Member II
My diesel guy ( who has serviced the engine ) has used Dextron III in ours. In fact, I just bought a quart due to what appears to be a slowly leaking drain plug (or bad washer??). Which, by the way, I can't get to budge.
Without hijacking this thread, any suggestions? Not enough room to swing my axe!
 

Tom Metzger

Sustaining Partner
The same guy at Hansen Marine who told me to use Dexron III also told me not to use the drain plug for draining. Since I never had I didn't ask him why. Probably because there isn't room to swing an ax. :cool: Or maybe because it will leak. Suck it out the top.

I stick a piece of copper tubing on the end of the hose of my oil sucker to be sure I got to the bottom of the housing.
 

Hagar2sail

Member III
Blogs Author
The same guy at Hansen Marine who told me to use Dexron III also told me not to use the drain plug for draining. Since I never had I didn't ask him why. Probably because there isn't room to swing an ax. :cool: Or maybe because it will leak. Suck it out the top.

I stick a piece of copper tubing on the end of the hose of my oil sucker to be sure I got to the bottom of the housing.
I’m thinking I might try our oil sucker as well, if I can get there. If possible maybe while it is still warm from motoring.
 

1911tex

Sustaining Member
Bob: Pour in some anti(stop)-leak for your drain plug drip...works in radiators under pressure...sure dont know about solid trans gears! Might Read the instructions, I have heard of folks putting it in leaky auto trans and rear ends with leaky gaskets back in the day. Or a viable option temporarily...a doggy or baby absorbent pad, stuffed under the tranny....may need changing every few months? I don't know why I keep coming up with these temporary crazy ideas.
 
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mordust

Member II
Good thought, so I looked on Amazon for those type products. Looks like they help rubber (or the like) seals and gaskets. I don't think we have those on the drain plug.
Already been through one pad. So I will muddle through, trying to remove the plug (bolt) without breaking, stripping or rounding. Then replace.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
My drain plug experience, FWIW.
 

Godzilla

Junior Member
Type A is the old GM trans fluid. It is difficult if not impossible to find new.
It has been superseded by Dextron II or III which is what an updated Hurth manual will specify.
You may need to read the fine print on the back new containers of ATF to see Dextron II and III compatible.
 

nquigley

Sustaining Member
My drain plug experience, FWIW.
Very useful, ... and timely ... Having changed my oil and replaced the oil filter last weekend (I've done this 3 times now - feeling like a pro at these processes), I was planning to tackle changing the transmission fluid this weekend, for the first time since buying the boat 4 years ago. I was thinking I could (just) suck the transmission fluid out through the dipstick hole (akin to sucking engine oil out of its dipstick hole) - is that not possible with the transmission dipstick hole? The process you went though to drain your fluid out and then refit the drain plug and washer sure seems like a hassle I'd like to avoid if possible.
 

1911tex

Sustaining Member
Very useful, ... and timely ... Having changed my oil and replaced the oil filter last weekend (I've done this 3 times now - feeling like a pro at these processes), I was planning to tackle changing the transmission fluid this weekend, for the first time since buying the boat 4 years ago. I was thinking I could (just) suck the transmission fluid out through the dipstick hole (akin to sucking engine oil out of its dipstick hole) - is that not possible with the transmission dipstick hole? The process you went though to drain your fluid out and then refit the drain plug and washer sure seems like a hassle I'd like to avoid if possible.
Yes suck it out...that is what I did. Not a problem. Be sure to check the new fluid level at the dipstick mark with the 17mm bolt/dipstick sitting on top of the threads...not screwed down. There was a recent detailed thread covering this process. Check it out.

Here is the thread mentioned...scroll down for the tranny info:
 
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