Thanks to everyone who replied,

Well I finally got the time and parts to get the head pulled and the distribution pipe removed.

Sure enough the pipe was filled with rust and junk back between the third and fourth slot. I cleaned it and the water jackets in the head and then reinstalled everything and got her back together and running. The car now runs cooler and the head is the same temp all over....finally.


Im supprised people dont just pull this pipe and leave it out, as it looks like a future problem waiting to happen. But Im sure Volvo in there supreme wisdom have it there for a good reason....but it was tempting.

Hopefully these pics of the Distribution Pipe will show up OK.

Cheers
Rob

Hi Rob: Sorry I didn't respond to this sooner. The exact same symptom happened on my 1960 B16B Amazon-S. Here's the link to my findings, that someone else may have already concluded:

Cameron's overheating problem / solution
--
Cam a.k.a. CVOLVO.COM

Latest update,

I drained the fluid and pulled the sending unit and checked as best I could the water passages around it. Head is clean and I could easily blow air into the head and out through the radiator / from both the sending unit hole and the pipe that connects to the hose going to the heater. I removed the thermostat and tried a number of combinations of blowing air and plugging holes, couldnt find any type of restriction. At one point I blew ino the head and forgot that the only way out was through a heater core full of coolant....can you say "Prestone shower"...damn that stuff is sticky.

I have a feeling the the guage in the car may be bad as well as it was reading 20 degrees higher than my IR unit. So a new one is on order.

I checked the timing and it is sitting at 12-degrees BTDC so next weekend I plan to back that down to 20-degrees.

I think the electric fan thermostst in the radiator comes on at a higher temp as well. So I will look for one with a lower start temp.

Thanks again for all the great information.

Cheers
Rob





Conclussion.............

Well after 18 plus responses, there are still some things that have not been covered or clarified.

1) Lets assume that the back of the head is actually running hotter than the front. Then a) the air/fuel mixture could be leaner in #4, possibly due to a vacuum leak, or b) the timing could be different in #4 than in the other cylinders ,or c) you could have a build up of carbon in that cylinder or a hot spot that triggers detonation.

We normally only time # 1 cylinder and assume that the others will come out the same, but with a worn dist. that is not always true. If the bushings are worn your timing will actually jump around. Do you get a steady line or a line that moves around when you time with a timing light? Does it stay steady at both high and low rpm?

2) You can have a number of problems with the coolant tube in the head - the one that runs fore and aft and directs water onto the sparkplug side of the combustion chamber throug small slots in the tube. These tubes can be loose - shake the head and see if it rattles. They can rust out. The slots can become plugged. The only way to be sure is to pull the freeze plugs out of each end of the head and take a good look, and you might even have to pull the tube. When I rebuild heads checking and reinstalling a coolant tube is a normal part of the proceedure.

And without going into details, don't believe everything you see here about fans and thermostats. If you would like to do a little experiment and learn something, run the engine with and without a fan, and with and without a thermostat.

No more time now, I have to pull out two coolant tubes.

John
V-performance.com

Your thermostat, supposedly, is fully open at 192° F. An operating temperature of 200° is not unusual. Particularly in summer, the temp needle in my PV is invariably just a fraction below the red zone when idling. I have also noticed that the rear end of the head gets hotter than the front. Maybe that's because there is less air circulation there, or maybe the air that gets to circulate there is warmer than up-front. I have another theory that no one has supported so far, but which came to mind again yesterday when I put on a new Ehrling head gasket. While the two coolant circulation holes up-front match the holes in the gasket nicely, even though the holes in the engine are tear-shaped and the ones in the gasket are round, the holes in the rear are halfway obstructed by the gasket, so, I've been opening up the holes in the gasket there, and that seems to make a bit of difference - not a whole hell of a lot though. All that said, however, after worrying for three years about the temperature gauge and trying most of the stuff the others have mentioned here, I simply decided to ignore it till the radiator boiled over, which it hasn't done yet, and I have enjoyed another four years of happy, worry-free motoring. The others here are tired of hearing my stories about this, so I won't repeat them, even though, you would be a welcome new victim ;-), but I have twice over-heated two different B16s to the point where the red paint turned grayish brown, with no other apparent harm done than blown temp gauges.
And, yes, running on seems to happen most frequently when the engine is hot, but can usually be mitigated by changing the timing and/or the mixture a little. It doesn't take a big change, and in my experience at least, there is no knowing in which direction to make it - both, richer and leaner and more advanced and more retarded, have worked for me. It may for you, but then again, it may not, but what can you lose?
Bob S.

Hi Guys,

Thanks for all the great information.

This weekend when I have some time, I figure I'll pull the thermostat sending unit. Hopefully I'll see something that might be causing the blockage, sure would beat having to pull the head off.

I will also check the timing to make sure it’s where it's supposed to sit.

Radiator is new with a 3 row core so I think that is covered, regarding the water pump, I’m not sure of the design but the motor was completely rebuilt less that 5000 miles ago, so the pump is new. The previous owner also installed an auxiliary electric fan in front of the radiator, but I have yet to hear it kick on.

Maybe a good backflush is also in order as I have yet to do that.

Ill keep you informed of my progress.

Cheers
Rob

I second Steve's comment about timing.
I run mine with 20° initial advance and they do great. Need about 60° dwell.
Retarded ignition (or insufficiently advanced) causes reduced power and overheating,
especially in the exhaust system but also in the engine. You gotta start the fire
early enough that you can get the power out of it before the exhaust valve is wide open.
--
George Downs Bartlesville, Heart of the USA!

A point that no one has touched on is TIMING. When I started my b18 bored out to 2 liter it was running hot. I had the timing set to the wrong side of TDC 10 to 15 degrees. The car started and ran reasonably well. It ran a whole lot better and cooler when I got it right. I say this because you mentioned that it runs on when you shut it down. Phil Singer had an article in Rolling a fwe issues ago that went into great detail on this very issue. I could send you a copy of it if you email me. My car runs indefinately at idle with no overheating now
Another possibility in the cooling department is the rad. The rad for the B18's is of a higher grade than the one for the B16's, you could consider getting a "Volvo" B18 rad not an after market one.
There is also a 5 blade plastic fan that came on the 122's I think, that is being used on a friends B20 in a 60 544 (with the smaller rad) and seems to do the job.
Steve

I spied a little clue in your post: "when sitting for a short time at idle, the temp guage will soar up to 200 F in no time"

Short Answer: Worthless stock radiator fan with no shroud really doesn't move air appreciably at idle.

Long Answer: There are two basic things the car needs to keep cool. First is coolant movement through the motor and radiator. The second is air movement through the radiator. The coolant movement through the motor is a more complicated issue, as there are multiple potential issues. But basically, if it is overheating at idle, it's almost ccertainly not a coolant flow issue. if that was compromised in some way (partically clogged radiator, partially clogged distribution tube, funky water pump, collapsed hose, dodgy thermostat, etc) then the primary symptom would be overheating under a load. When you are driving, the motor is putting out MUCH more heat, and without proper coolant flow the coolant bottled up in the motor will pretty quickly start to get hot. So if it overheats at idle, we can move on to the next issue: Air flow.

Volvo put a silly little egg beater fan on their old cars, with no shroud. I'm almost not sure why they bothered. If the motor is idling, the fan really doesn't do much in the way of moving air. If the motor is revved up, then most likely you are motoring along, and the air flow (well, vast majority of it) is provided by the air hitting the grille as the car moves along. Maybe if you are 'drafting' behind a big truck on the highway the fan is actually doing the work it was intended for, otherwise you could pretty much take it off an not miss it that much (slight exaggeration). Since practically no air is moving through the radiator at idle, it will overheat. My PV used to be able to sit idling and boil itself in about 5 - 6 minutes flat. Solutions? Install a better engine fan, like a flex blade like IPD used to sell. Or (even better, IMO) install a thermostatically controlled electric pusher fan in front of the radiator. That's what I finally did with my PV, it practically never kicks on unless I'm stuck in stop and go traffic on a warm day, or it sits and idles forever. Or after shutoff, it sometimes cycles on a couple of times which helps prevent boilover. And last but not least, just bump up your idle speed somewhat. The increased idle speed will spin the water pump and fan a bit faster, and they might actually be able to accomplish enough cooling to keep the motor cool.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

There are a couple of types of impellers in water pumps and one is better that the other. One type looks like a fan that is made of stamped steel much like an alternater cooling fan blades. This design has alot of open area allowing a bit of inefficienty of the pumping action. The next type is an impellar that is cast with a closed back and vanes that radiate either in a curve or perpendicular design. An example can be found on this site: http://www.evanscooling.com/main1.htm then click on coolant pumps (under: Competition & High Performance Applications). This last design forces all the coolant on it's merry way, were as the open design I'm sure you've all seen them, cannot pressure the coolant as efficently. I've descussed the merits with my napa jobber and they agree. The open impellar type is just cheaper to make. I think it's just one thing to consider when fighting the subject of our beloved getting hot.

Hello,

Yes the distribution pipe can get blocked.

I have pulled my fair share of silicone glue out these pipes.

But first, make sure the corret style of thermostat is installed.

It is very common to find that the incorrect style has been used.

The correct thermostat has a spring loaded extension on the bottom and this is to cover a small pipe in the head when the thermostat opens and which then correctly directs the flow of water through the head.

Without this extension the water never circulates correctly through the engine.

Eric
Hi Peformance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90501

Is it possible for the head to get a blockage in the water jacket? I have the factory Volvo manual and I noticed it has some strange "distribution pipe" in the head, can this get blocked????

Yes. you cut right to the chase, this subject happened to be my fist post as well, on my '66 but I had to do the whole runaround.

I had unidentifiable gunk trapped in there, seemed that the more I flushed the system, the faster the temp climbed. I guess it's a kind of bottleneck. Rod it out with something flexible, whatever it is isn't likely to be very solid.

While I was fooling around I installed a thermostat from a Jaguar XKE I think it was. About 10deg C cooler, so fully warm was around 160-165F IIRC. I was paranoid in hot hot Northern California. That car's apart right now, if it's of interest (and that 'stat is still in there) I could check.

Cheers,
-Sean
--
1966 122s, 1970 142s, 1974 142e... Blue is beautiful