2010 QSB 5.9 355hps in Tiara 3200 – any input appreciated

Hello Diesel Experts!

First time poster. Would greatly appreciate any insights, observations, or other feedback. Thank you so much for this resource and your time. Will try to keep this brief (ugh I see it’s not though). Under contract on a 2010 Tiara 3200 with original Cummins QSB 5.9 355HPs ~800hrs. I am in love, but not married yet, and def trying to get a hard peek behind the kimono first. I’m brand new to diesel motors and inboards but have tried to educate and equip myself with the vast knowledge on this site. I’m ~ 7/10 on DIY skill level, with experience maintaining Yam 4 stroke obs, houses, generators, etc.

Survey and sea trial were yesterday, I came and hired a good surveyor and an independent Cummins guy w the magic laptop. This cost a fortune but I would never forgive myself. Boat was commissioned this week after winter in yard. Dead cold motors fired up in 2 cranks each (whole other funny story re how I know they were def cold). <br />

Boat weight listed ~ 16k lbs (35 LOA, 13’ beam, 3’ dft),  Full fuel (256g) and water (38g) at my request plus 4 guys and tools on board. Propellers had some crud from last season but bottom clean. Weather was calm, 70’s air, 50 water. Couldn’t find a performance curve for a 355HP QSB 5.9, but THINK it’s same as 330hp – 2800 rpm rated and 2885 max (sure hope so…). Not sure if this was some special HP version for Tiaras bc I don’t see them anywhere else.

Motors made 2810 and 2820 WOT (98% “load”), avg of runs was 2800 both sides. I WISH I had filled out the custom table I made, printed, and brought for rpm/fuel burn/speed, w cross-refs to perf curves from Cummins and tiara, but I didn’t, and regret it.  @2810rpm boat made 28.6kts but idk fuel!  @2760 it was 18.1 g/hr each and idk how fast. @2600 rpm = 15.5 g/hr each = 27.3 kts. The mechanic was jamming on the vessel views and I just panicked and was so worried about rpms going above 2800 that I didn’t write anything down like a moron. But all the fuel burn readings i observed live were slightly higher than the Cummins curve for 5.9 330, which i’d studied before hand. Blowby at WOT w digital manometer (best meter name ever) never got above 6-7 on either. All seemed pleased by this.

Attaching a bunch of pictures of the engine room. What do you think fellas? Have receipts showing aftercoolers and HEs last serviced in late 2021 (top of list to service if we close), and injectors and tubes in stbd motor replaced in 2022 (weird). Current owner has had boat 2 years and done nothing except oil changes (and no receipts for those but oil is fresh now). Of course mechanic didn’t want to take elbows off to look at turbo exhaust or do any other bolt-removal stuff. I don’t think tiaras are know for doomed exhausts and I see raw water injection occurs downhill from riser. I thought both raw water pumps showed signs of leaking (or had been) based on rust below them, also rust around metal in lower aft of ER might be prior shaft seal leak (?). No leaks observed before/after sea trial (new seals).  Mounts, especially rubber bushings, look sketch, but seem to work fine during backdown test (per the experts). Sure I left a lot of info out but didn’t want to make this even longer.

Should I try to get seller to have ACs & HEs removed and serviced to make sure they’re serviceable before closing? It’s only been 2-3 years (in salt, no flush). Is that reasonable to ask? There are some other punch list things but the motors are my no. 1 and 2 concern.

Thank you!

Turge’