Volvo Penta 8.1 Exhaust Crossover/Equalizer

[Raft61]

Has anyone had problems with the 1.25" Exhaust Crossover Hose on a VP 8.1L V8? Last service, the mechanic replaced the hoses with incorrectly spec'd hoses (they used radiator hoses)!

I didn't realise but the one on the starboard engine blew a hole in it and (apart from spraying salt water over the engine), once the engine was switched off it would not start again and engine was making weird sounds which I can only describe as "compression leak". I tried a few things before realising that the exhaust Crossover/Equaliser Hose had blown a big hole in it. I replaced the hose with a correctly spec'd Exhaust Hose and all fixed! (just had to clean-up and treat all the salt water sprayed everywhere).

I meant to replace the hose on the port engine but didn't get around to it. This week, the port engine started playing up and the fuel pump was making loud noises. Thinking I had a bad fuel pump I replaced it. After fitting the new pump, the engine would start but then eventually stall. I thought I'd done something wrong with the fuel pump replacement, but then I realised it was making similar "compression leak" type noise that the Starboard Engine had been making when it had a faulty Exhaust Crossover Hose. Checked the Exhaust Crossover Hose on the Port Engine (which I should have replaced when i did the other one) and it has a small hole in it. I'm about to replace it hoping that this is what's causing the engine to stall.

Question to the group. Would you expect a faulty Exhaust Crossover Hose to have such a significant effect? What is the Crossover for anyway?

 

[Bondo]

Ayuh,.... Welcome Aboard,..... How much water do you have in the fuel filters,..??
That's the 1st thing I'd have checked, before changing the fuel pump,....

Change the bad hoses, Then diagnose yer issues,....

 

[alldodge]

Welcome
VP uses normal good quality heater hoses, same as auto. For the hose to blow just means it was cheap hose.

Don't know your setup but if its standard stock setup there shouldn't be anything What 8.1 do you have, would need to look it up?

 

[Raft61]

Thanks for the feedback. Stock standard twin VP engines 2006 8.1OsiB-F. The mechanic used "water suction and delivery hoses" which, when I look them up, are only rated to 60°C and not rated for exhaust fumes...

Anyway, when the first one failed, I wasn't aware and kept motoring. Wet Exhaust (salt water) was sprayed across the engine bay. When I stopped, the engine wouldn't start again. Got home and opened the engine bay, saw a bit of a mess and couldn't figure out what was wrong. Engine would turn over and try to start but just wouldn't, and it was making a kind of hissing sound like compression was escaping somewhere. I was thinking all the salt spray may have stuffed up electronics or connectors, or that salt water vapour had been sucked in through the air intake and stuck valves or something. Found the big burnt-out hole on the back side of the hose. I tried taping it up (just with gaffer tape to see if it'd make a difference) and the engine started up! Replaced the hose, cleaned up all the salt residue (over both engines). Used dilute water/vinegar followed by wash down with hot soap water and rinse with clean water. Both engines came up well and everything has been working well for a couple of months. I've been meaning to replace the hose on the other engine...

Last trip out, the other motor started playing up. Losing revs, rev hunting and eventually stalled. When I got home and turned ignition on the fuel pump was making very loud awful noise while it was priming. Engine would start but revs would hunt and stall. Was pretty certain fuel pump was cactus so I replaced it. Made sure I primed the filter with fuel (as ur supposed to) and tried starting the engine. It would start, idle for a few seconds but then slow down and stall. Thought it might just be a fuel supply issue and tried letting it priming a few times (turning ignition on and off) before trying to start but no difference. When started, if i tried to open the throttle the engine would stall immediately. I don't have a pressure gauge to check low and high fuel pressures (but can hear both pumps running during prime). I then realised that the sound the engine makes as it slows down and stalls, is the same sound the other engine was making when it had the blown hose. I checked the hose on this engine and it is burnt and has a very small hole in it. I'll replace the hose and see what happens from there.

(My main concern is that the salt water that was previously sprayed over the engine has caused electrical problems or has gotten into the air intake and stuck a valve or something nasty. Fingers crossed it's not that bad)

What I really wanted to know is, would you expect a hole in this crossover exhaust hose to be enough to stop the engine from starting?

I believe this exhaust Crossover/Equaliser Hose is actually there to provide exhaust "scavenging" for the engine cylinders (and maybe also reduce the possibility of water ingestion through the exhaust in VP's when at low revs). I have absolutely no idea what exhaust scavenging is or how it works.

 

[alldodge]

OK understand what you have. You want something like Trident wet exhaust hose. It's hard walled and cost around $12 a foot

When salt water gets sprayed around they is no telling what the next issues will be. Do need to test and it could be something like corrosion/bad contact.

Does sound right now like a fuel supply issue. Many of the auto parts stores will loan tools like a fuel pressure gauge. Need to test to determine which direction

Your parts breakdown
https://www.volvopentastore.com/Mar...on_id.308334333--store_id.366--view_id.765172