8-71 TI Temp

[Capt Chad]

Freshwater since birth 8-71 TI's in my boat. They have ran up to 180 when pushed up past 17-1800 rpm since I got the boat. Like most they build little heat at idle. Now my stbd. side tries to get up around 190 if I push them. Port is still hanging tough at 180. So I changed the impeller on the stbd. side with no change. I have never cleaned the heat exchanger. Nor do I know many that have in freshwater. So... how bad is pulling the HE and cleaning it and how bad is pulling the thermostats. I currently find myself lacking in the mechanic category unless I wait for Diesel Don to make his rounds. The manual states that I will need a seal puller for the thermostats that alone makes it sound tougher than any thermostat replacement I have done. Does anyone have a Part# for 170 thermostats for the 8-71s? Thanks

[SEVEN]

Go on to u tube and watch some videos on Barnacle Buster. When you replaced the impeller where all the fins attached? Hit both motors with a heat gauge while running. The gauge it self might be going bad.

[Capt Chad]

The old impeller looked good. I had it open so I replaced it anyway. I'm getting the temp reading on both stations. So it could be a sender I guess. Big problem is I have to be underway to get to the heating issue so it's hard to be at the helm and the ER all at the same time.

[Capt Chad]

Maybe I can bribe somebody to sit beside that 8-71 with an IR gun...

[MadHatter53]

If your anywhere near me I'll take a run with you.

[Scarlett]

My 8-71’s were doing the same thing and I just did the flush of the HE with vinegar, circulated for about 6-7 hours, ran today and temp stayed below 180 at all RPMs very happy with the results and pretty easy to do once I got all the parts together. John

[SEVEN]

You can switch the sending units from port to starboard to see if it’s the gauge

[Briankinley2004]

You can switch the sending units from port to starboard to see if it’s the gauge
or switch the gauges if you dont want to mess with the coolant going everywhere

[SEVEN]

or switch the gauges if you dont want to mess with the coolant going everywhere

Good point.

[SKYCHENEY]

You can do it. Get a slide hammer seal puller and change the seals and thermostats. I'll bet you have one that is not fully opening. With a freshwater engine, I'll bet its not the heat exchanger.

https://dieselpro.com/detroit-diesel-5132155-thermostat-seal-186780.html

https://dieselpro.com/thermostat-for-detroit-diesel-series-v71-92-170-degrees.html

https://www.harborfreight.com/heavy-duty-slide-hammer-and-puller-set-16-pc-63268.html

[Capt Chad]

Thanks, I think I'm going to go ahead and order a set of thermostats. Did they come with gaskets?

[sine]

I just replaced both of my heat exchangers on my 871 ti. After the replacement, they run just below 180 when running around 1900-2000 rpm.

[SKYCHENEY]

Thanks, I think I'm going to go ahead and order a set of thermostats. Did they come with gaskets?

Yes you'll get a paper gasket with them, but you'll need to order the seals separately.

[Capt Chad]

Thanks Skycheney. I Ordered gaskets separately but they can go into the box of spares. I located the thermostat housings last night while I was messing with another project. They point straight up toward the salon floor. The salon was carpeted pre-me. They covered everything but the center hatch. I have about 12" over the top of the housings. Has anybody pulled those seals without a slide hammer puller? Or am I cutting my carpet? Parts are supposed to be here Friday.

[SKYCHENEY]

I'm not sure on the 871's but I think the seals are in the top part that you will be removing. Take out on the bench to replace the seals.

Also, try dropping the old thermostats in a pan of water on the stove. See if they open fully and at what temp. I just used my IR gun.

[Capt Chad]

Thermostats made no change. In on my first hour of backflush with the Genesis method. I'll let you guys know how it works out.

[Boatsb]

Pull the he and get it cleaned at a radiator shop. It could be the closed circuit side.

[SKYCHENEY]

Pull the he and get it cleaned at a radiator shop. It could be the closed circuit side.

True. What coolant is in there? The green stuff or the newer purple PowerCool or such?

When was coolant last flushed/changed?

[Capt Chad]

The red Detroit stuff. I let it run in the slip for a while and they both came up to about 150 on the thermostat housings. Maybe that got it... Won't know anything until I run it.

No, I haven't flushed the closed side. What kind of coolant are you guys running?

[Boatsb]

Distilled water and napacool.

We dont get too much cold weather here.

[scottinsydney]

Its not often we can go faster than 900RPM in our local boating area and the engines never warm up. Rarely do we go above 1500RPM
.
Dieselpro has 160, 170 and 180 degree thermostats... would the 180 degree be my best choice? Any issues using a higher thermostat?

[Briankinley2004]

What ratio do you use on the NAPA Kool? Thinking of going that route next time I change mine as we dont get below freezing either and if so I have block heaters.

[kelpy]

Your heat exchangers will get scaled up in fresh water just like in sea water though to a lesser extent. Get them cleaned and resealed and you problem should go away. Never let those engines get above 190 degrees - not even for a second.

[SKYCHENEY]

The red Detroit stuff. I let it run in the slip for a while and they both came up to about 150 on the thermostat housings. Maybe that got it... Won't know anything until I run it.

No, I haven't flushed the closed side. What kind of coolant are you guys running?


DD Powercool and I check the SCA level yearly.

[SKYCHENEY]

Its not often we can go faster than 900RPM in our local boating area and the engines never warm up. Rarely do we go above 1500RPM
.
Dieselpro has 160, 170 and 180 degree thermostats... would the 180 degree be my best choice? Any issues using a higher thermostat?

Changing thermostats will not bring up the temps if you're only running 900rpms. Stick with 170's and at least you're good when you do run 'em up.

[scottinsydney]

Thanks. What thermostats would the fzctory have installed when they were built?

[SKYCHENEY]

Thanks. What thermostats would the fzctory have installed when they were built?

All marine DD's should run 170's. Others may disagree but I've had several mechanics tell me that. If you give a DD dealer your serial number, they can tell you what the original part was.

[Boatsb]

What ratio do you use on the NAPA Kool? Thinking of going that route next time I change mine as we dont get below freezing either and if so I have block heaters.

Theres a recommended concentration on the jug that I follow. I usually keep it a bit high so when I fill with distilled a bit theres no big drop.

[Capt Chad]

I pulled the intercooler off today and backflushed them. All I found out of normal was oil. So I inspected the Turbos and found too much end play on the shafts.

Even at the slip I noticed one engine was 20 degrees hotter on the exhaust ports on the manifold than the other side.

Have you guys seen an overheat caused by Turbos going out? Too much exhaust restriction?

[racclarkson@gmail.com]

What ratio do you use on the NAPA Kool? Thinking of going that route next time I change mine as we dont get below freezing either and if so I have block heaters.Or just go with Power Cool premix. About same price as concentrate. If your system is tight and you use overflow tanks you should never have to top off.

[scottinsydney]

I ran the motors up to 1450 rpm which is the absolute maximum I will ever go for the next 20 years due speed restrictions. Used my IR gun on the thermostat housings and recorded about 167 degrees for both engines. Why can I not necessarily use replacement 180 degree thermostats? My thoughts are they will solve the issue of running cool engines. Nobody will drive the boat except myself. The old thermostats can be stored for a future owner.

[racclarkson@gmail.com]

I ran the motors up to 1450 rpm which is the absolute maximum I will ever go for the next 20 years due speed restrictions. Used my IR gun on the thermostat housings and recorded about 167 degrees for both engines. Why can I not necessarily use replacement 180 degree thermostats? My thoughts are they will solve the issue of running cool engines. Nobody will drive the boat except myself. The old thermostats can be stored for a future owner.No reason. Do it.

[SKYCHENEY]

You state that you normally run at 900rpms. The 180's will make absolutely no difference in temps at that rpm because they will not even start to open same as the 170's or even 160's. Do as you wish but you will likely see no change. To get the temps up, you need to run them at higher rpms.

[Briankinley2004]

Put one in forward and one in reverse and advance throttles to 1800. I bet you come up to temp and dont violate the speed restrictions. I personally agree with Robert on this

[scottinsydney]

The farmers in Australia refer to spinning a car around in a paddock as "Circle Work!" Perhaps I could try this on my boat in front of the Sydney Opera House. I'd be sure to be breath tested by the water police.

Anyway, the issue at hand is IF the engines will generate enough heat at 900RPM to increase the coolant temperature to around 180 degrees?

If anyone has a parts book, the blue tag on the engine says SN 12VA077581 and the thermostat is #76.

Cheers.

[Photolomy]

What is the full range of RPM's for 8V71TI engines in a 53' boat, and what should the temp be throughout?

[kelpy]

167 deg. at 1450 RPM or so sounds about right.

Changing thermostats to increase the operating temperatures at low load/RPM is as fruitless as changing injector size to get better fuel economy. Detroit Diesels just don't work that way.

[Capt Chad]

Well, I pulled the heat exchanger because it was the only thing I haven't had apart. It looked like it was brand new... I pit it all back together. I lot it to check for leaks. I have water spewing out of the week holes in the inner cap on the outgoing side of the cooler. I know something happened to one of the o rings. Anybody ever had this happen?

[Scarlett]

Wait a minute Scott, I seem to remember someone else driving your boat a few weeks ago, and by the way enjoying it a lot. John

[KPTIM]

On the thick plate / spacer on the out going side of the heat exchanger.
That plate has to go on facing the correct direction.
If you put it on reverse / backwards water will come out of those small weep holes.
It is very easy to install it wrong.

The other cause for this is if you use the wrong after market O-rings and also can happen if you do not replace the crush ring that goes between the two O-rings.

[scottinsydney]

1. SCARLETT is the only foreign captain to have driven my boat down Sydney Harbour. I enjoyed sitting on the front deck talking to Mrs Scarlett in the sunshine. 2. Is there a parts diagram to explain the orings and plate associated with the outlet side of the heat exchanger?

[Capt Chad]

I think my heat exchanger wasn't exactly straight on the outlet side. I used the old metal seal to tap the new one in. I'll bet I crushed the new one a little. Anyway, new gaskets and seals ordered. I'll dry fit everything this time before I snug anything up.

[Capt Chad]

Like I said, the heat exchanger looked great. It's definitely not the cause of my overheating. In still without answers.

I had a guy suggest the pressure cap? What do you guys think? I will of course try it. I have tried everything else. It would make sense that after this year long quest it would be a $15 item.

[Fanfare]

I don't think that would cause overheating unless you are losing coolant through the overflow drain.

As I recall, 8-71s require an 8 psi cap. Don't go to a higher pressure one.

[racclarkson@gmail.com]

Starting to sound like the water pump needs a rebuild.

[Capt Chad]

Pulled the boat out today. The clamshell/water intake grate on that side had taken a lick at some point but nothing bad enough to impede water flow. In short I saw nothing to point at the overheat problem. I'm out of ideas.

[Capt Chad]

Robert, were you referring to the raw water pump or the circulating pump?

[racclarkson@gmail.com]

Robert, were you referring to the raw water pump or the circulating pump?The coolant pump, freshwater circuit, front of motor.

[Capt Chad]

Well, it's the only thing I haven't had apart. What the hell, why not.

[Capt Chad]

Anything special needed besides the kit?

[racclarkson@gmail.com]

Anything special needed besides the kit?Have you got the book? I can check later if needed.

[racclarkson@gmail.com]

BTW, I hope you are planning to run some descaler through the freshwater coolant side. Might be a good idea to do that before you start tearing down.

[Capt Chad]

Just got the boat back in the water from a haulout to locate a vibration and get some bottom paint. I have ordered the kit. So, being that I am hauling 5 gallon buckets up and down the dock to get rid of old coolant and for any flushing. What IS recommended for a 1 time flush before I pull the pump off?

[Briankinley2004]

I used the cascade powder dish detergent. Mix up a cup full in some warm water then add to distilled water in the engine. Several diesel mechanics have suggested this to me and it seemed to work

[racclarkson@gmail.com]

I used the cascade powder dish detergent. Mix up a cup full in some warm water then add to distilled water in the engine. Several diesel mechanics have suggested this to me and it seemed to workI think the cascade is good if you have oil in the coolant. Penray 2001 or 2015 are good choices. Whatever you use, you’re still gonna need to flush the flush. I wouldn’t bother with distilled water for flushing. Use that or pre-mixed coolant for your final fill.

[Photolomy]

This is a timely thread for me. Is this the proper sequence to flush/clean the fresh water side of the cooling...

1. Add gallon of Penray 2001 to each engine.
2. Run for 20 minutes.
3. Drain.
4. Fill with regular water.
5. Run for 10 minutes.
6. Drain.
7. Inspect (using endoscope).
8. Replace Zincs.
9. Fill with 50/50 distilled/antifreeze.

[racclarkson@gmail.com]

This is a timely thread for me. Is this the proper sequence to flush/clean the fresh water side of the cooling...1. Add gallon of Penray 2001 to each engine.2. Run for 20 minutes.3. Drain.4. Fill with regular water.5. Run for 10 minutes.6. Drain.7. Inspect (using endoscope).8. Replace Zincs.9. Fill with 50/50 distilled/antifreeze.i disagree. 1/2 gallon of Penray per 8 gallons of coolant. So keep count of what you drain. Also, zincs are on raw water side. They don’t enter in this job. Endoscopes are fine but won’t tell you much on coolant side. True test is condition of the flush water. Not clear, needs more work. Regarding earlier post re Cascade, DW detergents don’t completely dissolve in water under 130 degrees. Therefore, pre mix that in a pot of boiling water and add to your fill bucket for best results.

[Photolomy]

Thanks!

For some reason I thought the coolant capacity (8v71ti) was 13 gallons, but now I see it is 7 gallons, so 1/2 gallon per engine.

[racclarkson@gmail.com]

Thanks!For some reason I thought the coolant capacity (8v71ti) was 13 gallons, but now I see it is 7 gallons, so 1/2 gallon per engine.I think you’re referencing a non-marine configuration. The HE will double or triple that figure. For example, my book shows 12-13 gallons; the reality is 24 gallons. That’s why it’s important to know how much came out.

[Photolomy]

Yes, that is where I got the 13, from the book. I will measure it as I drain it. That is going to be a lot more antifreeze ($$$) than I expected.:)

Also, I will be doing the raw water side as well, and the Genesis method (referenced in threads) seems to be pretty good?