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Volvo 850, x70 oil cooler line block off testing in progress...

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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rspi
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Re: Volvo 850, x70 oil cooler line block off testing in progress...

Post by rspi »

Hey Guys and Gals, I do apologize for not updating this page years ago, here you go. I still remove those lines as soon as possible when I get another turbo vehicle. Actually, you don't have to remove them, you can disconnect the oil cooler thermostat, pull it away from the engine, slide the block off plate under it and secure it to the engine and leave the system hanging. I now leave the system and remove it the next time I have more access like I do when replacing the radiator or something like that.

Below is a link to the video with the lab results and more.

https://youtu.be/LGbgetmn90M
'95 855 T-5R M, Panther - 22/28 mpg, 546,000 miles
'95 955 T-5R Yellow Wagon, Lemonade, 180,000 miles
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BlackBart
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Post by BlackBart »

My '94 T-5 cooling lines are leaking oil on the forward / radiator side of the block. I had planned on replacing those with a modern aftermarket hose and oetiker clamps, and new gaskets. I have a write-up with pics floating around here somewhere. Is the block-off plate at the oil thermostat low on the engine, or where these hoses attach to the side of the block?
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Post by foggydogg »

BlackBart wrote: 30 Jul 2025, 21:35 My '94 T-5 cooling lines are leaking oil on the forward / radiator side of the block. I had planned on replacing those with a modern aftermarket hose and oetiker clamps, and new gaskets. I have a write-up with pics floating around here somewhere. Is the block-off plate at the oil thermostat low on the engine, or where these hoses attach to the side of the block?
The bypass plate takes the place of the thermostat housing, where the lines plug into the engine.
I use limb loppers to cut the lines into pieces. They come right out.
I've got a whole stack of them out back.
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abscate
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Post by abscate »

Life in an old thread. I’m sure they intend is to use fullsynthetic oil in a turbo with this mod. 5000 mile OCI, 3000 OCI if you cant stay off the boost or live in the nasty hot places, or short trips

on edit - fixed drunk post
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Post by BlackBart »

I'm reviving my memory of fixing this issue. The only reason we parked this car was because it was spraying oil all over the front of the block.
Screenshot 850 oil cooler lines.png

I dug up the parts diagram to understand the routing...
GR-68412.jpg
GR-68412.jpg (23.5 KiB) Viewed 316 times

Read and watched Robert's DIY's.
Read through this seemingly complicated process of replacing them with new....
Volvo 855 Oil Cooler Line Replacment rev0.pdf
(6.06 MiB) Downloaded 23 times

And dug and dug to find the thread about making your own with industrial Volvo blue hoses. That's what I was going to do, seems simple.......maybe.... And LOOK, Sir Abscate, Oetiker clamps!!
viewtopic.php?t=86914
20181007_121222.jpg
20181007_121222.jpg (156.21 KiB) Viewed 316 times
But after reading Robert's comments about no significant cooling happening with this system, I think I'll go with the cover plate and bag all this.
https://www.ipdusa.com/products/56831/O ... _jVBbEN4CZ

Sometimes these are on ebay for less.

Questions - Robert detaches the right / passenger US side motor mount and lifts the engine. Is that necessary to access the hardware on the thermostat housing?

Is there oil in the radiator cooler that should be drained?
ex-1984 245T wagon
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Post by Sveedy »

I'm thinking that this system isn't really an "oil cooler", but more of an "oil equalizer". The water heating up transfers to the oil to help it get up to temperature quicker. Think Sweden in the winter :shock:
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Post by abscate »

Sveedy wrote: 18 Aug 2025, 10:52 I'm thinking that this system isn't really an "oil cooler", but more of an "oil equalizer". The water heating up transfers to the oil to help it get up to temperature quicker. Think Sweden in the winter :shock:
Oil temperature definitely lags coolant on startup. It probably also helps on high torque/boost pulls when the turbo is working hard - oil can shoot up to 260F and coolant will pull that down.
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Post by jreed »

Thanks for that 'blast from the past' PDF above -- I had forgotten about that. Those new lines I installed back then are still working well with no leaks noted yet. I did buy a backing plate and gasket in case the hoses spring a leak again -- may use those instead of putting in new lines / rebuilt lines.
1997 855 GLT (Light Pressure Turbo) still going strong. Previous: 1986 240 GL rusted out in '06, 1985 Saab 900T rusted out in '95, 1975 Saab 99 rusted out in '95, 1973 Saab 99 rusted out in '94

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Post by BlackBart »

My tires still aren’t mounted, but the car is up on jackstands, so I dove in to remove this system.
There is no need on mine (‘94 T5) to loosen the motor mount and raise the engine - it’s right there visible behind the plastic fender liner.
The T40 with a medium extension popped the thermostat / manifold right off. Figured out the hose clips on the radiator, popped the lines off. Fought to get a tiny 10mm on the oil pipe bracket blind - I just pried the bracket apart and made room. Snipped the hoses so I could twist and wrestle the pipes out the passenger wheelwell.
Some oil dribbled out, medium brown. I may push more out of the radiator with an air hose. Need to find the box with the new cover and o-ring, clean up the oil, and bolt it up. If anyone wants a functioning thermostat manifold it’s yours for shipping.

So much more room around the radiator on that side now!
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ex-1984 245T wagon
1994 850T5 wagon
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