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Velvet Drive Overheating

rich_p

Regular Contributor
'87 1:1.91 behind 454 Crus

'87 1:1.91 behind 454 Crusaders. New raw water pump. New "U" cooler. One year old heat exchanger. Risers and elbows guessing about 3 seasons but very little rust from the nipple when I replaced water hoses last week. New overheat sensor. Rebuilt other trans about 4-5 years ago due to loss of forward & reverse.
I am at the point where I am going to pull the trans and put in a spare since I can not get this thing to run cool for longer than 30-45 min. Any suggestions before I cram myself into positions the human body is not meant to be in?
 
"It will be messy but you may

"It will be messy but you may want to check the oil hoses. They may have collapsed internally. You're 22 years old. If they're original, just replace them and give her a whirl.

Good luck
Rick"
 
I've replaces the oil hose

I've replaces the oil hoses but not sure when the last time was. Was planning on new when the trans got swapped but can try before and see if it helps.
 
"Look at it this way: Since y

"Look at it this way: Since your plan includes new hoses anyway...IF it works, you've saved a load of work. If not, you're only out a few hours if that."
 
"If the tranny is not slipping

"If the tranny is not slipping, the fluid is up, and the hoses are good, I'd check out the sump filter. If clogged, the cooling circuit flow would be low."
 
"I think "strainer", o

"I think "strainer", on the return fitting, is accurate.

If the hose change and the strainer don't improve things, I'd do a pressure test to assess the pump and regulator. there isn't much else to go wrong.

What type of fluid are you filling the gears with?"
 
"So I pulled the two hoses tod

"So I pulled the two hoses today and will replace tomorrow (30 kt winds didn't have me too motivated). Found it odd that there was not much fluid in the lines or cooler. From what I remember other times when I changed these lines there was a good ammount in there and had to deal with catching fluid and cleanup. It did sit for 24 hours but I think there should be more fluid in lines/cooler. I don't think there is a filter and will look for a strainer tomorrow. It has one line running from the top of the reduction and one from the port right next to the overheat sensor, where should I look for a stariner? Fluid was type F but after an overheat was changed to FA. Any ideas?"
 
"On some, there's a filter

"On some, there's a filter behind the fitting on the lower right side (of the line going to the heat exchanger).

Jeff"
 
"did you blow out the cooler t

"did you blow out the cooler to see if it was clogged?

Isn't hard but sure can be messy.

You should have a strainer or a shield, in the case, when you pull the bushing that the return line connects to. either one should have a notch in it that ensures correct orientation in the case when it is reinstalled. You may need a pick or a small 'hook' tool to remove it."
 
"Oil cooler is new and not clo

"Oil cooler is new and not clogged. Ratio is actually 2.10:1. Cooler return line is plumbed to top rear of reduction.
New hoses, no filter on lower right side, new type FA fluid. Still running hotter than other. Plan is to swap it out with a 1.91:1 to get through rest of season and rebuild the 2.10:1. I am starting to think that it is actually slipping at higher speed. Was originally thinking that might have fuel delivery issue since engine will get to 3150 rpm but anything over that it is a solid jump to 3500+. If bring it back as slow as possible, at ~3470 it will drop right back down to 3100. Theory is it is slipping once past 3100 and heating fluid. Once again, any thoughts appreciated before the swap tomorrow afternoon."
 
"If you're gonna swap gear

"If you're gonna swap gears, I'd still suggest blowing out the 'new' cooler. If the old gear is slipping, those 'parts' usually wind up in the cooler...not point in going thru the swap exercise only having to do it again before you planned.

An optical tach on the coupler is a good way to verify the slipping, if you have one available. The sudden RPM jump is a good indication of slip but not definitive by itself."
 
"So finished the swap. Long st

"So finished the swap. Long story short, the sticker that says what rotation the output is is wrong.
angry.gif
Put gear in F and the shaft spins opposite of the arrow and boat goes in reverse. Time to rebuild."
 
Why would this spin the opposi

Why would this spin the opposite direction?
They are both green label. The original one that is slipping is a 10-18-007. I put in a 10-18-005. Shouldn't these have the same rotation? Am I missing something?
 
"On BW transmissions with a 1.

"On BW transmissions with a 1.91:1 ratio,, the output shaft rotates in the opposite direction from the input shaft. it is the only BW reduction ratio designed like this.If you have a LH engine you need a RH prop and vice versa.
Joe"
 
"rich:

Joe is correct about


"rich:

Joe is correct about the 1.91 having the output rotation opposite the input. Same goes for the 1.88's, too.

The label gets applied when the engine rotation is selected by way of the pump housing orientation. It is quite possible the 1.91 was coupled to the opposite rotation engine when the label was applied and somewhere between then and now the pump was reversed."
 
"Are you sure both are 72C tra

"Are you sure both are 72C transmissions. Looks like one of your transmissions was replaced at one time. I had the same issue. Stb. transmission was much warmer than the port transmission. I then realised that the port was a 72C and the Stb was only a 71C and undersized for the engine. Four years later the 71C is still operating much warmer, but just fine. I am going to run it till it dies. I change the transmission fluid a bit more often."
 
"Technically swapping the redu

"Technically swapping the reduction gear would solve the problem is my new understanding. Not that I want to do a reduction gear swap, but it is possible?
The end result is the 1.91 will come out. The 2.10 will be rebuilt (hopefully drop off Monday and back quickly) and put back.
1.91 was a take off for the port engine replacement I acquired a month ago (needed the engine, not the gear). Most likely will wind up back on that engine and sold as a engine and trans once I rebuild the engine that came out of the boat.
The joys of owing a boat (I currently have 5 in the water, I should be committed)"
 
"swapping the reduction unit i

"swapping the reduction unit is possible but I'm not sure it is a simple R&R. Looking at the breakdowns, the 1.91 units are a bit different than the others. I'd visit the shop and ask.

You've got FIVE floating??? Given the new administration, I'd be looking for a federal flotilla subsidy program...they've got to have one by now."
 
I'm starting my own armada

I'm starting my own armada.
In water:
36' Pacemaker Sportfish
25' Catalina
19' Baja
15' Boston Whaler
9' Yamaha GP760
Also a Sunfish and inflateable ready to go
 
2.10 is at the shop and should

2.10 is at the shop and should have it ready in two days. $750 is what I was told to expect on the rebuild.
 
So the rebuilt trans is still

So the rebuilt trans is still overheating. The engine stays cool. Only thing left "old" on the cooling system is risers and elbows. Since the engine stays cool can I assume that there is enough water flowing through at speed or should I do a riser/elbow change and hope for everything to stay cool?
 
"That's dissapointing. Ar

"That's dissapointing. Are you sure there is sufficient Dexron fluid? For it to overheat quickly, it pretty much has to be slipping."
 
Fluid is good (although ge

Fluid is good (although getting drained again after overheat). Alarm goes off around 30-45 min of running at speed. Will be looking for a optical rpm and high pressure gauge.
 
"Rich - may be a long shot but

"Rich - may be a long shot but did you check the 'new' switch to see what temp it turns on at? (or use another measurement to check the switch; IR gun, etc?)

what coondition is the fluid? If still pink and clear with no odor, I'd suspect the switch. You can also install a pressure gauge on the gear."
 
I thought it was the switch an

I thought it was the switch and that was the first thing I cahnged when it started. IR gun and the temp is definately overheat. Think fluid is still pink/clear but will know when it comes out tomorrow for sure.
 
"Rich:

the only thing I can


"Rich:

the only thing I can find left is the shift cable and control.

Have you verified the shift lever on the gear is fully engaged when the control lever goes to FWD?

If dual station setup, you need to verify the shift lever moves properly when both controls are used."
 
"Rich; since you have an IR g

"Rich; since you have an IR gun, you might check the trans oil temps at the cooler. I've never had the trans oil too hot to touch. I'd expect an input oil temp similar to the case temp, and an output temp of maybe 20 deg down. If the delta is much higher, the oil flow may be compromised. If both temps are very low, then I'd say that oil is not flowing much at all. I think you said the cooler is new, so a zero delta with hot oil is unlikely. If you get a 20 deg delta with 200+ going in, then the tranny is low oil or slipping or ???"
 
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