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Overheating Amazon

9K views 22 replies 8 participants last post by  Ron Kwas 
#1 ·
Over the last few months I have been fighting an overheating amazon!

I bought the car at the end of summer and drove 400 miles with the heater core open and the fan blowing 130 degree to keep the engine from overheating! Since that torture I have been working to remedy the problem without success.

- Replaced Water Pump
- New Radiator Cap
- Flushed and treated with Thermocure
- Flushed and treated with weak mixture of Citric Acid
- Back flushed the system multiple times
- Tested Capillary Style Thermostat and the measurements are confirmed via thermocouple and IR gun.
- 160 Degree Thermostat helped substantially but still the symptoms did not subside.
- I've got uneven heating across the block with #4 running hotest and #1 running coolest.

Yesterday I drove 8 hours from NC to GA and the ole girl did great for the first 5 hours but then on the last two the temps crept into the red and then I had to open the heater core until the end of the trip (60 MPH on backroads).

My next steps are to have the radiator boiled out, check the distribution pipe for any blockages or corrosion, and potentially flush the system again!

Thoughts?
 
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#2 ·
The back of the head running hotter than the front of the head is normal at idle. Temperatures tend to even out once the engine is running faster.

Check to make sure that the distribution pipe in the head has not come loose.

The correct thermostat should have a flap on the bottom of it. When the thermostat opens up this flap moves down and closes off an internal recirculation pipe just below the thermostat. If that recirc pipe does not get closed off coolant can by-pass the radiator causing the engine to run hot. Some thermostats lack that flap or the flap is not correctly positioned and fails to close off the pipe completely.

The bottom 1/3 of the rad on my 142 had a blockage 1/2 the way across the rad (crossflow rad on the later 140s). You could hold your hand against the fins and move it across the rad and the temperature drop across the blockage was obvious. Sending the rad out for a caustic bath and a pressure test (in case the bath unblocks some holes in the tubes) made a huge difference.

These days, you can buy digital multimeters with a temperature sensor probe for less than $100. With a long enough probe, you can slip the probe under the clamp on the top hose at the rad and run the lead back into the car. This would allow you to directly monitor the exit coolant temperature from the engine block which is about as good as it gets in terms of measuring the average coolant temperature and what the thermostat is doing. This would confirm whether you have an actual overheating problem or the gauge is doing flakey things.
 
#3 ·
Paul;

Good info from 142G...additionally, and FIRST, I'd make certain Cooling Sys is filled...many times an overheating engine can be traced to an insufficiently filled (or circulating CS) caused by air stubborn air bubble...also, make certain you can trust the temp indicted (check calibration of Temp Gauge!)...then, I'd pressure check the system to assure it can hold the Pressure Cap pressure (makes CS more efficient and effective than at atmospheric)...check temp difference from Rad top (input) to Rad output with for instance an IR thermometer to assure Rad flow and heat shedding is effective...if you notice significant amount of deposits when looking into the Radiator, you can figure that is also occurring at the Coolant Distribution Pipe withing the Cyl head, and that can lead to reduced flow to cylinder further from the WaPu...removing CDP from Cyl Head and enlarging the coolant distribution holes is possible and has helped some, but that should only be undertaken as one of the last attempts at a solution...that and installing an electric cooling fan (which will help with cooling when overheating at low speed/low Rad airflow rate), but if you experienced overheating at highway speed after a long trip, I suspect coolant flow is the issue, not air flow.

See additional details on all these points here: http://www.sw-em.com/Cooling_System.htm

Good Hunting!
 
#4 ·
removing CDP from Cyl Head and enlarging the coolant distribution holes is possible and has helped some, but that should only be undertaken as one of the last attempts at a solution...that and installing an electric cooling fan (which will help with cooling when overheating at low speed/low Rad airflow rate), but if you experienced overheating at highway speed after a long trip, I suspect coolant flow is the issue, not air flow.

See additional details on all these points here: http://www.sw-em.com/Cooling_System.htm

Good Hunting!
Ron:

I was interested in your comments on the coolant distribution pipe because I am suspicious that mine has come loose and might have rotated. Your final comment 'see additional details' had me scurrying to your site. I know that the pipe is supposed to be swedged; but, I was interested in the details of how you would refit a loose pipe. Unfortunately, all I could find was

Umlaufrohr einsetzen, geht nur in einer Position, verstemmen und neuen Insert pipe, this is only possible in one position, displace metal to secure in place

Can you possibly elaborate on the 'displace metal to secure in place'. Is this something more than whacking the end of the pipe with a brass drift to try and get it to stay in place? I am tempted to try a version of the coolant pipe modification; but, just opening up the #3 and #4 holes. I can monitor the old D jet sensor at the front of the head and I have an electronic gauge / sensor at the original temp sensor location. I know that when the car has been in continuous motion the distribution pipe and flow rates work just fine with the front of head and back of head temperatures being within a couple degrees C of one another. Its the idling stuck in traffic on a hot day when you can see the back of head temperature climbing and the front of head where the thermostat is located thinks everything is just fine.
 
#5 · (Edited)
142G;

It's more likely your CDP has crystalline blockages impeding flow than having rotated out of position...because the CDP end has a keyhole cross-section, so it is pretty unlikely for it to rotate...and displacing the remaining metal which protrudes once the tube is in place is more to keep it in place longitudinally. See pix near the end of the CDP article: http://www.sw-em.com/Coolant_Distribution_Pipe_Notes.htm [I should rewrite that description a bit better and to that effect.] I'll get some pix with better detail next opportunity, unfortunately, these will have to do for now...

" Its the idling stuck in traffic on a hot day when you can see the back of head temperature climbing and the front of head where the thermostat is located thinks everything is just fine. " If coolant is flowing through a free Rad, and it's just at idle, cooling should be enough for a long time, because there is not that much extra heat being generated (that's why it is much faster to warm up the car in the winter while driving, than just idling in the driveway)...trouble is if there is additional heat in the engine and it lags behind the cooling capability of the CS (like coming upon a traffic jam on the highway after just running at high load, generating high heat, but now the Rad cannot shed that heat), that is the worst case...add to that maybe being in Arizona with only hot air for the Rad, and one might very well have to install an ECF to help assure decent airflow.

Cheers
 
#6 ·
Thanks Guys! Ron your website has been an immense help over these last few months!

I will start with a pressure test and record the temperature difference across the radiator and hunt for any blockages in the core. Then I will make arrangements to have the radiator cleaned professionally, hopefully it doesn't spring a leak after the caustic bath! I will also pick up a replacement expansion plug for the head so that I can clean the distribution pipe with my pipe cleaning kit.
 
#7 ·
Paul;

Having the Radiator cleaned or "boiled out" and flow checked is a good start (and if it leaks after that, it was near failure anyway, so finding it during this test and when its out and can be repaired is not necessarily such a bad thing...!), and while CS is empty, flushing out block is also a good idea...remove rear petcock, and vary a direction of vigorous flow...catch and inspect what is flushed out...and if you're going "all the way" then pulling the CDP to inspect level of blockage by crystallization of distribution port (and possible slight enlargement) would be next.

Good Hunting, please let us know what you find, if any particular one thing...but many times, it's all the cumulative of multiple smaller factors.

Thanks for the kind words.
 
#8 ·
Good News!

While setting up my pressure testing equipment I gave the engine a quick lookover and found that the fan belt was extra loose. That makes perfect sense why on my road trip the temps were normal for the majority of the trip and then started to climb towards the end of the ride. The generator must have rattled loose and allowed the belt to slip on the water pump pulley. I've ordered a new fan belt and will replace in the coming days.

I will keep this thread updated if the overheating reappears.
 
#9 ·
Paul;

Given the symptoms of a normally running engine overheating after hours of highway running, i'll believe an "extra loose" FB caused the issue...that simplifies things immensely!...just inspect Generator pivots below (well) and also tighten them well also to prevent recurrence...they like to work loose and oval their holes.

Cheers
 
#10 · (Edited)
I had a similar situation... My '67 B18 showed it was running hot when I first picked it up, but it was manageable. In the process of going through everything, I pulled the motor and did a bunch of head work and nearly a full rebuild of all the bearings, changed the cam etc while the car was being painted. I even put in an aluminum rad with a super high flow electric fan. Put it all back together, and first run the temp gauge pinned to the hot side within the first 10 minutes. But there were no other signs of running hot. I had put a Saab temp switch near the rad outlet to drive the fan, and but fan hadn't kicked in, so the exit temp of the coolant couldn't be more than 95°C... So i borrowed an IR thermometer and read the temp at the back of the block, it was just fine. My old gauge was just reading wrong.

I ended up swapping out my old gas filled gauge with an electronic one and it works just fine.
 
#11 · (Edited)
35;

...that's why troubleshooting to root cause is always preferred and recommended (...and I realize that's tricky with Cooling System with its capillary tube connected sensor!)...as one of the first things, when overheating or truly running hot is indicated, I recommend checking calibration of the Temp Gauge...and this must be performed with extreme care and caution! (See: http://www.sw-em.com/temperature_gauge_notes.htm )...I'm not poo-pooing your nice modification...I would consider it also if the Gauge was stone dead, and worthless as an indicator, but your case, the situation could have been brought under control, and your concerns eliminated (and a lot of time and expense spared), by noting where the needle pointed when Sensing Bulb was placed in boiling water, and placing a sliver of yellow tape there...

Cheers
 
#12 ·
An easy way and through way to clean the coolant distribution pipe is to use industrial strength Safety Kleen carb and parts cleaner that is used in the company's immersion cleaners found in shops and garages; we have one here in the shop. Take the basket out of the unit and put the head in so it is standing on end with more than half of the head immersed and leave it there for 5-6 hours or overnight. Next, take the head back out, turn it over and soak the other end for the same amount of time then remove and flush or soak with a naphtha-based parts cleaner and the tube will as clean as when it was new and all deposits will be gone. It works better than a hot tank will.

Or soak the head in CLR (calcium-lime-rust) cleaner available in good hardware stores. It will remove all of the deposits on the tube.
 
#13 ·
An easy way and through way to clean the coolant distribution pipe is to use industrial strength Safety Kleen carb and parts cleaner that is used in the company's immersion cleaners found in shops and garages; we have one here in the shop. Take the basket out of the unit and put the head in so it is standing on end
Thorough, probably. Easy, not so much unless the head happens to be off and you just happen to have an immersion cleaner out in the garage. Lacking a fully equipped shop, my definition of easy would be something that you dump in the radiator prior to doing a coolant change:). However, if I ever do take the head off again I will give consideration to the CLR treatment.
 
#14 ·
It does not like Georgia. Bring it back to NC and it will do fine, I can take care of it!! ( I still kick myself for selling my 123GT) I had one B18 block that would erratically overheat. I was actually rallying it at that time and using it as a daily driver to boot. I had a newer engine which had been decked, head shaved and everything redone, swapped it in and that engine ran cool.. When I tore down the overheating engine, a bunch of what looked like rocks came out. Some one said that is may have been left from the casting process. I just joked that it was a Monday engine. If you need, I do have a spare radiator at my shop which I would be willing to part with.

Derswede
 
#16 ·
I have some overheating issues as well if I can borrow this thread. 1965 Amazon with a B18 engine, the temp sensor usually sits at 75%. I decided to look into that a few years ago, replaced the thermostat to a 92°C one (197°F). The old was a 87°C/188°F one but I didn't know that when I ordered it. Maybe the 87°C one would've been better since it's only driven in the summer but anyhow...

The car started running way hotter, climbing into the red on the sensor. I removed the radiator and flushed that, I think I used a bottle of some radiator cleaning liquid, flushed the block etc. Even replaced the water pump even though the old one turned out to be fine. For some reason I put the old thermostat back in and it went back to the old 75% on the sensor.

I'm not sure if I should invest any more time and effort into this? Is the original temp sensor reliable enough to be trusted or should I just keep driving it as is, the way it has been the last couple of years? I saw video of a guy using a machine dishwasher detergent thing pill in his Volvo 240 and it kept spitting out old rusty red water. That's the only thing I haven't tested, but not sure if I have to.
 
#18 · (Edited)
I removed the radiator and flushed that,
You need to take it somewhere to have it boiled. There's no other way to get out the crud, rust and scale of ages. Afterward, paint it with a good black paint and your overheating problems will be over (assuming your water pump etc are ok).

The stock tstat is 180F, btw. That's 82C so I'd suggest taking yours down a notch come summer (or right away, if you don't need a ton of cabin heat).
 
#17 · (Edited)
Schmoyo...;

In looking at the calibration marks on the Instrument, and adding one my own for 90ºC, I have to question if your engine was overheating in the first place, and your concern was maybe misplaced! I have added some reference indications for both 87 and 92ºC T-Stats to a picture...have a look...do you still think your engine was overheating?
Gauge Speedometer Auto part Technology Measuring instrument

Source: http://www.sw-em.com/temperature_gauge_notes.htm
If you have flushed the Cooling Sys and indication hasn't changed, that's good, and in combination with the info above should help you answer your question if you should trust the Gauge, but info for checking calibration can also be found at link.

Cheers
 
#20 ·
I agree with tmtalpey. On a B20 (and I expect the B18) the OEM thermostat would be 82 C. There is a slightly lower temperature thermostat which is an option. According to the official Volvo service manual, the 82 C thermostat starts to opens at 82 C and is not fully open until it reaches 90 C so under normal conditions the temperature gauge will move in that zone as driving conditions change.

My 142 is for non winter use; but, I have driven it in cold temperatures before the snow arrives. With an ambient temperature of -10C and travelling at 110 km/hr with the interior heater on full blast the engine temperature drops to around 80 C. That suggests that unless my thermostat is leaking, its fully or close to fully closed and if you are looking for more heat in cold weather on the highway there is nothing to be gained by running a thermostat that is hotter than 82C. Switching to an 82C thermostat should eliminate the high temperature readings that you are getting and provide you with as much heat as you are going to get on the highway.
 
#21 ·
I've assumed it's probably fine since it has survived like this for so long, but it hasn't felt good. I think the current thermostat is 87°C (which at least for my old 240 used to be the "summer" thermostat temp you'd want) and that the needle sits just around 87-90°C on the gauge, so that's good to hear! However with the 92°C thermostat I think it might've climbed near the 100°C mark on the pic. I haven't messed with it since 2015 so I don't remember exactly, but it got hot to the point I didn't dare drive it anymore. But maybe that was just on account of my misreading the gauge anyway.

Thanks for the help, all of you! :)
 
#22 ·
Was in the shop a few days ago and noticed that the generator was a bit out of alignment with the fan and crank pulleys. So I pulled the generator and noticed the root cause of my "overheating issues".

See below,

I wanted to drill out a larger hole and use a large bolt but decided to simply use 3/8 bolt and nut, ensuring that the tension was set using the arm and then lock in the bottom bolts.

Fingers crossed the belt doesn't slip on my next road trip to North Carolina.
 
#23 · (Edited)
Paul;

Taking a long trip based on "fingers crossed" is not my idea of fun!...but now that you have identified the cause, just make sure the Fanbelt stays tight for the trip, and you should be fine...drilling out and increasing hardware size is OK also, just make sure you use self-locking hardware (ie Nylock nuts at least, or double nuts) to secure Gen as vibrating loose was totally typical (I think I saw it on every Generator equipped car I ever worked on!), and once loose, oval holes [and in your case, a loose Fanbelt with overheating, to say nothing of what the Charging System was (or wasn't!) doing]. resulted...and when you're ready for a little more electrical oomph, you know where to look...!

Cheers
 
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