Volvo Tamd 71B Issues (Overheat & Hard Starting)

[Marty3412]

Good evening guys/gals, Just looking to pick some brains regarding a couple of faults which are bugging me on my Volvo tamd71b. I have found many very useful posts on this forum however none have quite hit all the nails on the head.

For some background info its in a workboat used for charter/survey work and is 10m on a single shaft.

The issues:

Overheating
The work the boat is on means it spends a lot of time slow steaming at around 1700/1800rpm probably barely enough for the turbo to be working, in this case the temp will sit happily at 80deg. The issue comes when stepping on the throttle (anything over 2krpm) the temp will steadily increase and will soon arrive at 100deg before you inevitably have to back off.
Thus far i have checked the following
-Thermostat removed and brought up to operating temp. Stat opens as expected without issue and closes once cooled.
-Coolers have been off and cleaned before the engine went into the boat (engine has always had this fault so for me unlikely the issues)
-Raw water Impellor is replaced every 12months and is always in good condition.
-Raw water flow from the exhaust is very strong during all rpm's suggesting raw water flow is good.


Thoughts on the next action for me would be to inspect the fresh water pump, and im wondering if anyone has had the same issue? I may also possibly remove the thermostat and give it a run see if that makes any change.


Hard Starting

More noticeable when cold, although it is apparent when warm (warm ambient before engine is first started for the day) . Engine takes alot of cranking to get going, the cold start device on the pump seems to make very little difference. Lift pump has been overhauled by a volvo diesel and when this was changed all pipework and copper sealing washers. There appears to be fuel to the engine when left overnight (Filter bleed screw can be crack and fuel will spurt out after 1 pump of the primer or so). Also when cranking with the injector pipes cracked off, it doesnt take much to get fuel upto them.

Could it be possible that these engines just dont like the cold, or as the hours of the engine are unknown be a issue with compression, i am keen and thankful to hear anyones experiences.


If all else fails i have a Cat C7 sat in the garage which will be going in (although ill be giving up approx 80hp.


Many thanks

 

[QBhoy]

Hi there. Although I’m not exactly familiar with the 71. I’m a fair bit familiar with the 61. Fairly similar for the most part. Few things I’d perhaps mention after reading what you’ve said.

I’d think at 1800 rpm, you should still have a bit of boost in play at that. Wouldn’t worry about that too much.
Just thinking about when she gets a little warm near higher rpms…what rpms are you seeing when she does this ? They aren’t very high revving engines at WOT to be fair.
but also thinking more around when you say this is in a commercial work boat set up. I’d perhaps wonder around the set up for taking in raw water through the hull. Is it sufficient enough and taking in plenty of water ? Also I’d ask about the sea strainer that’s fitted. Is it definitely sealing well and not drawing air in ? Most of these engines in the leisure boat installation set up, will be planing speeds when near full throttle, perhaps usually taking in serious amounts of water in through the intakes, just by the pace through the water alone (additionally to the draw from the pump). Perhaps your intakes aren’t as sufficient as they need to be ?
obvious things like oil condition comes to mind…but you’ve no doubt rules that out by now.
Does she alarm on the dash when she gets warm ? Is it worth verifying the gauge is accurate by testing the ohms at the temp sender unit ?
Little chance of it, but is the header tank cap doing its job ? Sealing ok ? If these are past their best, they can prematurely relieve the systems pressure, resulting in an increase in temperature whilst doing it.
hope that helps a little for now.

 

[Portofino]

Overloaded.

Check the prop size and it’s hygiene .


Also accounts for the cold st .The exhaust valves mushroom = loose compression .

 

[QBhoy]

Overloaded.

Check the prop size and it’s hygiene .


Also accounts for the cold st .The exhaust valves mushroom = loose compression .

Excellent point about the prop Portofino. Fair play. I think I perhaps dismissed the hard starting in my comments, so the the chance it could be battery related. These things need serious juice to start cold. Hard starting could also be a sign of a strong high compression engine too, of course. Lots of variances that could see this. Battery, cabling condition, starter condition and of course the old heater plugs not being allowed to do their thing from cold. Big stone crushing old school lumps these things, as you’ll know. Even the 61’s take a strong strong battery to start from cold. One of the 61’s in the princess starts much easier than the other. But I’d say if anything, the one that’s harder to start (which can verge on flattening its battery of left for more than a month), might be considered a little stronger performing than the easier to start. Both very strong engines either way.

 

[Marty3412]

Hi there. Although I’m not exactly familiar with the 71. I’m a fair bit familiar with the 61. Fairly similar for the most part. Few things I’d perhaps mention after reading what you’ve said.

I’d think at 1800 rpm, you should still have a bit of boost in play at that. Wouldn’t worry about that too much.
Just thinking about when she gets a little warm near higher rpms…what rpms are you seeing when she does this ? They aren’t very high revving engines at WOT to be fair.
but also thinking more around when you say this is in a commercial work boat set up. I’d perhaps wonder around the set up for taking in raw water through the hull. Is it sufficient enough and taking in plenty of water ? Also I’d ask about the sea strainer that’s fitted. Is it definitely sealing well and not drawing air in ? Most of these engines in the leisure boat installation set up, will be planing speeds when near full throttle, perhaps usually taking in serious amounts of water in through the intakes, just by the pace through the water alone (additionally to the draw from the pump). Perhaps your intakes aren’t as sufficient as they need to be ?
obvious things like oil condition comes to mind…but you’ve no doubt rules that out by now.
Does she alarm on the dash when she gets warm ? Is it worth verifying the gauge is accurate by testing the ohms at the temp sender unit ?
Little chance of it, but is the header tank cap doing its job ? Sealing ok ? If these are past their best, they can prematurely relieve the systems pressure, resulting in an increase in temperature whilst doing it.
hope that helps a little for now.

Hi qbhoy thanks for your comments,

the questions about the raw water intake scoop was asked when the hull was made and trialed, as far as I can see there is no issue, seachest is clear and shows no signs of airation during any load. Plus combined with the visible water flow out the exhaust flush I’m happy this isn’t the issue.

anything over say 2k/2.1k when the engine starts working will see the temp creep up. I did have thoughts regarding if the engine was just simply overloaded however when pushed it does exactly what you needs and happily makes the power, no black smoke etc.

 

[Nauti Fox]

For cold starts there is an air heater element in the inlet, check that's working

 

[volvopaul]

Coolers blocked on the fresh water side , remove the stacks and dip the whole assembly in rydelime then jet wash , rebuild coolers with new seals etc , you may find the housings badly corroded .
also check exhaust elbow for corrosion inside where water exits, if it’s the later elbow make sure 3 of the tabs are bent away from the outer casing to allow more water past .

 

[Marty3412]

Coolers blocked on the fresh water side , remove the stacks and dip the whole assembly in rydelime then jet wash , rebuild coolers with new seals etc , you may find the housings badly corroded .
also check exhaust elbow for corrosion inside where water exits, if it’s the later elbow make sure 3 of the tabs are bent away from the outer casing to allow more water past .

Will pull them out this week, it doesn’t have the factory elbow on anymore so that eliminates that I guess.
It’s the speed that it goes from being ok at 80 to well over 100 which has me doubting the coolers, although I will be checking them regardless

 

[QBhoy]

Will pull them out this week, it doesn’t have the factory elbow on anymore so that eliminates that I guess.
It’s the speed that it goes from being ok at 80 to well over 100 which has me doubting the coolers, although I will be checking them regardless

Marty, I’d be tempted to check the gauge is giving a true reading too. Just in case. Also what I was saying about the header tank cap not venting pressure too. Easy things first. You might be lucky. Other than that…sure sounds like a cooler issue. Might be worth pulling the drain plug and see if anything crappy looking in physical form or colour comes out it. Might give you an idea

 

[QBhoy]

Suppose you could also make sure your sea cock is fully open too. Often there can be play in the spindle enough to think the valve is actually opened fully (by handle position), but it’s not quite getting full open and the flow. Worth a look anyway. See how it feels back and forth, might give you an idea.
is the boat able to plane or are we talking a displacement hull ? Is everything original as built spec and did it defo not do this before ? Also wondering about this different exhaust elbow you have too, since you’ve mentioned it.
But I’d defo check the ohms from the gauge if you can. See what it’s putting out. Perhaps see if you can get a handheld temperature reading gun too. See if it’s a genuine situation you’re getting for temp. I’ve got the manual somewhere and can check the specs for max tolerated running temp that’s acceptable…but often gauges can read up to 10 degrees off actual temp. See if you’re losing coolant from the header tank if you can too.

 

[QBhoy]

Just came to mind there that I know the 61’s run over 80 degrees on load. Perhaps show around or just under 90 from memory. If you’re running at 80 then it’s shooting to 100 quickly, you may have a t stat issue. Can’t remember if you said you’d checked these already.
Edit***think the t stat is 75o on yours perhaps.

 

[Marty3412]

Suppose you could also make sure your sea cock is fully open too. Often there can be play in the spindle enough to think the valve is actually opened fully (by handle position), but it’s not quite getting full open and the flow. Worth a look anyway. See how it feels back and forth, might give you an idea.
is the boat able to plane or are we talking a displacement hull ? Is everything original as built spec and did it defo not do this before ? Also wondering about this different exhaust elbow you have too, since you’ve mentioned it.
But I’d defo check the ohms from the gauge if you can. See what it’s putting out. Perhaps see if you can get a handheld temperature reading gun too. See if it’s a genuine situation you’re getting for temp. I’ve got the manual somewhere and can check the specs for max tolerated running temp that’s acceptable…but often gauges can read up to 10 degrees off actual temp. See if you’re losing coolant from the header tank if you can too.

We have some down time in the coming months so i have plenty time to play around, next run out im going to verify all the temps with a digital thermometer, i guess that will give an indication of how the stat is working and the efficiency of the coolers. Although the coolers were stripped and flushed prior to the boat owing to them leaking when running up on the test bed it arrived on so im doubting slight scaling is causing the sharp temperature increase im getting.

Its been sniff tested not so long ago (exhaust gas in coolant test) and it showed nothing.

The exhaust eblow fitted is just a replacement for the original cast volvo part, just a stainless eblow same ID as originals with a feed for raw water in. Rather than the eblow being salt water cooled its heat wrapped. Doesnt really offer any changes and i ran the same set up on my old boat with twin tamd61b with no issues.

Hoping to get some pics of what i find

 

[QBhoy]

We have some down time in the coming months so i have plenty time to play around, next run out im going to verify all the temps with a digital thermometer, i guess that will give an indication of how the stat is working and the efficiency of the coolers. Although the coolers were stripped and flushed prior to the boat owing to them leaking when running up on the test bed it arrived on so im doubting slight scaling is causing the sharp temperature increase im getting.

Its been sniff tested not so long ago (exhaust gas in coolant test) and it showed nothing.

The exhaust eblow fitted is just a replacement for the original cast volvo part, just a stainless eblow same ID as originals with a feed for raw water in. Rather than the eblow being salt water cooled its heat wrapped. Doesnt really offer any changes and i ran the same set up on my old boat with twin tamd61b with no issues.

Hoping to get some pics of what i find

Good stuff. All sounds good. Hope you get to the bottom of it. No doubt you’ll get a better idea after a good look around her next time. Good luck with it and keen to know how you get on.

 

[gordmac]

Does the oil pressure drop off when the engine gets hot? I had a similar problem with a Ford, found the problem was the oil cooler. A non contact temperature device was invaluable in finding the problem.

 

[Marty3412]

Done some digging, amongst other things the water pump was found to be erroded inside, meaning the tolerance between the impeller and casing was significantly larger than it should have been. Recon penta pump has been fitted, we’ll see how she does under load when the turbo stater and alternator are back from recon.