Semiahmoo
Member
- Joined
- Sep 24, 2013
- Messages
- 41
- Status
- OWNER - I own a Hatteras Yacht
- Hatteras Model
- Not Currently A Hatteras Owner
For future reference for others who run Detroit 671 naturals:
Had oil residue getting into the freshwater system. Family friend who has decades of experience turning a wrench on these things (but too old to do so now) said to first look at the gear cooler at the bottom of the heat exchanger. He said it's a pretty simple/straightforward job.
Fast forward about a month - had a local shop do the job. They initially pulled the cooler and sent it out for cleaning and testing. It was gunked up bad. Test said "no leak". Detroit guru saw the pic and said BS. Twin Discs run at high pressure - 300-400 psi. If its only tested at around 30 PSI he said the leak often won't show and warned me not to put that old cooler back in.
New cooler ordered.
New cooler installed.
System required four flushes to get oil residue out.
Take boat out for a three hour tour - runs great. (it never did run bad - just oil residue spotted in overflow tank which started this whole thing) No oil spotted in system yet. So far it looks like problem is solved.
BUT
Got the bill though – 30+ hours total to diagnose, remove, clean coolant from bilge, install new gear oil cooler, flush once, twice, three times, four times etc. (I figure there was some travel time from the shop to the boat in the slip as part of that 30+ hours)
I was stunned. I’ve had coolant flushes on big diesels before that took about a day for BOTH engines. Granted, that’s a single flush but 30+ hours for four flushes!!???
At $155 per hour you do the math – this one gear cooler swap cost me about what I could pay for an entire running 671 take-out including shipping!!! (Not including installation cost of course)
Damn I love boating but not these kinds of bills. If my back wasn’t so hinky I’d have crawled down there and did it myself.
Okay, ranting grumble is over.
If any others have this same issue with oil getting into your freshwater cooling system on this era of Detroit 671 naturals (1970s/1980s) make sure you look to the gear cooler first.
Then I would strongly recommend that after the new cooler is installed that YOU do the coolant flushing and save a sh*t ton of $$$$ on what is a relatively simple/straightforward (albeit time-consuming) repair.
(Also wanted to add that the mechanic who did the work was a very nice older gentleman who clearly wanted to do a good job - I just never imagined the coolant flush was going to be that time consuming.)
Had oil residue getting into the freshwater system. Family friend who has decades of experience turning a wrench on these things (but too old to do so now) said to first look at the gear cooler at the bottom of the heat exchanger. He said it's a pretty simple/straightforward job.
Fast forward about a month - had a local shop do the job. They initially pulled the cooler and sent it out for cleaning and testing. It was gunked up bad. Test said "no leak". Detroit guru saw the pic and said BS. Twin Discs run at high pressure - 300-400 psi. If its only tested at around 30 PSI he said the leak often won't show and warned me not to put that old cooler back in.
New cooler ordered.
New cooler installed.
System required four flushes to get oil residue out.
Take boat out for a three hour tour - runs great. (it never did run bad - just oil residue spotted in overflow tank which started this whole thing) No oil spotted in system yet. So far it looks like problem is solved.
BUT
Got the bill though – 30+ hours total to diagnose, remove, clean coolant from bilge, install new gear oil cooler, flush once, twice, three times, four times etc. (I figure there was some travel time from the shop to the boat in the slip as part of that 30+ hours)
I was stunned. I’ve had coolant flushes on big diesels before that took about a day for BOTH engines. Granted, that’s a single flush but 30+ hours for four flushes!!???
At $155 per hour you do the math – this one gear cooler swap cost me about what I could pay for an entire running 671 take-out including shipping!!! (Not including installation cost of course)
Damn I love boating but not these kinds of bills. If my back wasn’t so hinky I’d have crawled down there and did it myself.
Okay, ranting grumble is over.
If any others have this same issue with oil getting into your freshwater cooling system on this era of Detroit 671 naturals (1970s/1980s) make sure you look to the gear cooler first.
Then I would strongly recommend that after the new cooler is installed that YOU do the coolant flushing and save a sh*t ton of $$$$ on what is a relatively simple/straightforward (albeit time-consuming) repair.
(Also wanted to add that the mechanic who did the work was a very nice older gentleman who clearly wanted to do a good job - I just never imagined the coolant flush was going to be that time consuming.)
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