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  #1  
Old 04-27-2012, 12:27 AM
ian2000t ian2000t is offline
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Default Changing Thermostat easy?

How quick does everyone's D24T take to get up to proper temp?

Mine is about 5 minutes to the halfway mark if you are driving it normally (but going easy on the throttle 'til it's warm). But, lately due to roadworks I've been spending the first 10 mins sat in traffic. During this time, just idling, it's just about reaching the quarter.

So, I'm thinking my thermostat might need changing. Or is this normal for a diesel? Is it an easy job to change?
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1990 Volvo 765 D24Tic (factory UK spec Tic). Monark 273 nozzles 163bar, Ajusa MLS gasket, 16psi, Water Injection, 17" Titans with 25mm H&R spacers, running 85% WVO/SVO.
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  #2  
Old 04-27-2012, 04:56 AM
piper109 piper109 is offline
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They are not quick to warm up but not dramatically slow either. Is the heater slow to warm up also? Normally any Volvo should have a good heater.
When its good and warm does the needle always reach the same point? A bad thermostat (stuck open) will show low on the temp gauge all the time and the heater will blow cool.

The thermostat is easy to reach and a cinch to replace, down on the lower part of the LH side of the block ahead of the injection pump and fuel filter. Just follow the hoses.
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Old 04-27-2012, 06:50 AM
ian2000t ian2000t is offline
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Heater is nice and warm. On a cold morning, if it's sat idling in traffic, it takes 5 mins for it to blow proper heat. Yeh, once it's up to temp it's up there for good then.

I know what you are saying about the bad thermostat constantly sitting cool, but I had similar on my Mini - started taking several miles before it was properly warm. New 'stat fixed it - warms up nice and quick now.

Ok, might get a genuine Volvo one and give it a go. What I should have asked rather than "is it easy", is : "what's going to break and disable the car if I try to change it"...
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1990 Volvo 765 D24Tic (factory UK spec Tic). Monark 273 nozzles 163bar, Ajusa MLS gasket, 16psi, Water Injection, 17" Titans with 25mm H&R spacers, running 85% WVO/SVO.
http://i103.photobucket.com/albums/m...AG0269-sig.jpg
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  #4  
Old 04-27-2012, 09:13 AM
piper109 piper109 is offline
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Make sure you dont strip the bolts that hold the thermostat cover on. Clean the thermostat seat well. If your thermostat flange has a small hole in it, orient it to the top. Make sure the o-ring is on the correct side of the thermostat flange. Check while you are taking the old one off :-) Nothings going to break !!

Be very careful when you are filling the engine back up with coolant. Its sometimes tricky to get all the air out as the thermostat can limit circulation till its open.
Put the heater on full hot before you fill. Personally I like to disconnect the highest hose (like the one that goes to the cold start thingy) so I can see that coolant has reached the top. Run the engine for a while, check the coolant reservoir. When you think all is well, go for a short drive and then check the coolant reservoir again.
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  #5  
Old 04-27-2012, 01:47 PM
ngoma ngoma is offline
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Quote:
Originally Posted by piper109 View Post
Personally I like to disconnect the highest hose (like the one that goes to the cold start thingy) so I can see that coolant has reached the top.
+2 on that, it helps to run out the air bubbles.
Smear the bolts with anti-seize to make it easier to disassemble next time and protect the bolts against corrosion.

Regarding the slow warmup at idle: This is common for diesels; they don't produce a lot of heat unless worked, much different than gassers. Might want to try covering the radiator during the winter. You may have seen large diesel trucks running with winter radiator covers for this reason.

Generally mine warms up to operating temp within 2 - 5 miles driving thru the city streets, depending on conditions.

The Volvo water temp gauge is notoriously inaccurate. Mine jumps to midspan within a minute of starting on a cold morning and I know it can't have warmed up that much that fast. There is some sort of signal buffer at the gauge that dampens the needle's movement, making it act more like an idiot lamp.
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  #6  
Old 04-27-2012, 10:00 PM
v8volvo v8volvo is offline
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Genuine Volvo is a good idea for sourcing the T-stat, but if you can find a Wahler unit that is fine as well. In fact, if you get one from Volvo, inside the blue Volvo box you will find ... a Wahler thermostat. So, really, you don't have much of a choice. All roads lead to Rome....

Also, be ready for a pretty big mess when you take the housing off, and again when you pry the old T-stat out of the block. Since the VW/Audi (/Subaru) convention puts the thermostat low down in the cooling system, you lose a lot of coolant when you replace it. Still an easy job but not quite as painless as a redblock or whiteblock Volvo with the t-stat right up on top, where you only lose a pint or two of fluid when you open it up. Overall the design difference is worth the slight added mess and hassle though, since it means if we run low on coolant in our diesel Volvos we won't have the thermostat sitting high and dry and consequently closing just when coolant flow is needed most... like our friends in the gasser Volvo world might experience.

Also worth noting -- Most D24T's from 1984 onward came with a nice little coolant drain petcock located in the plastic tee piece where the lower cold start thermostat hose connects to the heater return hose, just adjacent to the thermostat housing. If your car has this, it may help keep the coolant mess contained somewhat if you drain the engine using the petcock before taking loose the t-stat housing. The petcock is even set up so that you could stick a piece of hose onto it, to direct flow straight into a container of your choosing. Just another one of the nice little thoughtful Volvo touches that you find on these cars from time to time.

Be careful to counterhold the female side of the petcock assembly with a second wrench, though, if you decide to use it. The plastic tee piece that the drain is located in can break if it is asked to absorb the force of loosening stuck threads...
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  #7  
Old 06-10-2012, 02:43 AM
240diesel 240diesel is offline
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I also was wondering about warming-up-time and made a measuring a time ago;

http://d24t.com/showthread.php?444-T...=3434#post3434

I also read the method of bleeding air and i agree, the best is to take of the small hose to the coldstart thermostat on the dieselpump.
I made several repairs to the cooling and heatingsystem and copied a trick from DAF; i made a line from that hose to the expansiontank, just like the little bleedinghose fram radiator>>expansiontank.

http://www.volvo700vereniging.nl/node/39065

The explanation is in dutch but it's easy to understand, the T- joint is soldered myself and also equiped with a electronic sensor to resd the actual temp.

maybe it's helpfull?

Maybe it is helpfull.
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