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overheating no vac no boost

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

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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overheating no vac no boost

Post by drjurman » Wed Jun 05, 2019 7:55 pm

Someone tell me if I'm toast.
98 V70 AWD
Lower radiator hose let go on the highway, literally a 12" rupture. had to drive another 6 minutes to get safely off the road.
Shut down called a tow. replaced all hoses upper, lower, overflow, splice, and turbo return. Also did thermostat. Drove it tonight about 20 minutes, got home reservoir was boiling over, not steaming, boiling
Car barely runs now, either it's revving at 3-4 grand or stalled. DTCs read all 300s 0300, 0302, 0303, -0305. Not 0301 (strange)
did plugs through dist cap, no better. I can run it providing I caress the throttle. Vac/Boost gauge reads between -5 and +1. Oil pressure good, no brake boost, need both feet to stop. Can't tell if the turbo is spooling but a +1 boost I think not.
This engine was rebuilt 50k miles ago, will I have to rebuild or are there any ideas what to look for.
I love this car. Just rebuilt the front end, and rear. Totally bent new fuel and evap lines 316 stainless. Lots of work. dont want to scrap it. :cry: tia

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Re: overheating no vac no boost

Post by ecbsykes » Wed Jun 05, 2019 8:56 pm

5 mins of driving on highway with no coolant? Sounds like it's toast. I'd get one of those test strips that check for exhaust gases to confirm, but these engines do poorly when overheated.


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Re: overheating no vac no boost

Post by scot850 » Wed Jun 05, 2019 10:26 pm

+1 on this unfortunately. I would do the coolant test as suggested.

Now there may be one thing to check. Try raising the front of the car on axle stands and run the engine to warm. As you lost most of the coolant, it may be you have an air-lock in the system near the thermostat which is where the coolant temp sensor is. See if this helps get the air out of the system. It may bubble over a couple of times. Worth a try.

Next thing to check would be the cylinder compression.


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Re: overheating no vac no boost

Post by Sommerfeldt » Thu Jun 06, 2019 12:24 am

I may be having a brain fart, but why are you getting no vacuum? Your brake booster should build some no matter what, with its check valve. If you were getting numbers that low "naturally", due to compression loss, I'd expect the engine not to run at all. Or am I being super confused...?

You should definitely do what the other guys said, though - test compression and for exhaust in the coolant. If your coolant reservoir is actually bubbling, it's coming in the "wrong" way. There's something not right with the circulation, so bleed the system like Neil said.

- S

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Re: overheating no vac no boost

Post by wizechatmgr » Sun Jun 09, 2019 11:18 pm

Remove the thermostat entirely for a drive. Then once the engine is cool, reinsert it after topping off coolant. As others have said, it's likely air locked.

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Re: overheating no vac no boost

Post by davidrjurman » Mon Jun 10, 2019 8:13 am

Hi all
Apparently my last post disappeared into the ether. I did a cylinder pressure test and these are the results.
1-5 warm 120 psi 8 cranks
wet 1 = 160 2-5 = 145 8 cranks
Don't think the turbo is spinning.
Cant find any Vac leaks.
Haven't done a block test, but I think I cooked it.
I guess pulling the head is next. Unless there is another point to look at.
Issues at present
Won't idle, No Vac low vac, 'no boost, only codes at present P0172, 0302 - 0305 but not 0301.
Has to idle above 1250 to be drivable
On the road slow response but stable, WOT no boost.
As far as the overheating changed out temp sensor, fan relay, found fan motor seized and blade melted off spindle.
When last checked fan was working, starting to wonder if it was intermittent and then locked up.
Just in case, does anyone have a good head they'd be willing to part with.
It the 5254 is cooked, i have a spare 5234 block I can rebuild.


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Re: overheating no vac no boost

Post by tardcart » Thu Jun 13, 2019 9:09 pm

that five minutes must have felt like an hour. Ive gotten out of my car on busier roads and sprinted across traffic just to save a turtle, I'm sure you could stop for a poor volvo. I wouldn't bother using any of that engine since the rings may be burnt in addition to head warped. the fact the oil increased the compression shows cylinders is scored. Im going out to check my lower hose with a flash light now. its only 23 years old but...
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