Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: Harry on January 04, 2015, 02:19:01
-
Both my Haynes and Autobook direct thermostat removal as easy as removing the four bolts that secure the top of the housing, moving that out of the way, lifting out the old, dropping in the new and replacing the housing top. I don't think so. Two of the bolts that secure the housing are blocked by the fuel injection lines where they are routed in a group around the front/side of the valve cover.. It sure looks as though the job will require removing thru entire housing from the block to gain access to all four bolts. That looks like a significantly bigger job - alternator, maybe radiator, etc. Am I seeing it wrong? Car is running about 140 instead of 180.
-
Yes, this job can be a real pain. I used the search function "thermostat replacement" is the title to find a bit more detail. When I replaced the thermostat in my 280 SL, I ended up removing the thermostat housing, and that made the job MUCH easier. It is not really that difficult. The angled hose under the housing required a little patience, but is manageable. If the bolts on the housing are not stuck (which is usually the case) they can be removed without disassembly of the injector lines. Be sure to put anti-seize when putting it all back to together. Also pay attention (as is noted in the thread about the replacement) to the orientation of the new thermostat.
-
Good idea to pick up some radiator hoses from at the same time for a little preventive maintenance. I bought my upper from the Classic Center and the lower from a qualified after-market supplier.
-
Jonny B - when you say thermostat housing, I assume you men the entire housing and not just the top of the housing immediately over the thermostat? My 230 also has a/c which may tend to complicate things a bit. I'll try the search thread you recommend. Thanks so much!
-
Yes, forget re-moving the housing if you have AC. You may have to remove the injector lines, depending on what tools you have to use. Sometimes you can just move them out of the way without complete removing them.
-
I need to investigate removal of the FI lines. The car is running so well that I hate to even touch those but it would surely make the thermostat replacement much more straightforward. Also, these lines seem to be quite accessible. Is their removal simply a matter of disconnecting and reconnecting? No bleeding, etc. required?
We took the car on a short trip last week and absolutely enjoyed the experience. It is hard for me to get comfortable with the highway RPMs, though. At 70 MPH, I am turning about 4,000 RPM. The car seems quite "happy" but the driver is a little uncomfortable about it. :)
Thanks again,
Harry
-
On my car, I did remove the entire housing to allow clear access to get the top cover off. My car does not have A/C and as Joe types, that is in the way.
There are quite a number of threads about the removal and restart with emptied injector lines. Most of the time you can just crank the engine and the lines will eventually fill. There are some other techniques, so just do a little searching and you should get the information you need.
-
Hi Harry,
High revs is what the engine is designed for. For the first few months of ownership of our Pagoda, I automatically kept trying to change into 5th gear - with a 4 speed box I never did find it :D
After a time, it just becomes the ..."song of the Pagoda" and now it has become music to my ears ;D
-
Jonny - indeed. I recall my father having these cars when I was much younger and the speed limit was 75 MPH. He routinely would run 85 - 90. It's just so long ago and cars nowadays run at such low RPMs that it takes some adjustment on my part. The car ran beautifully and was super nice to drive.
-
I often use heat to remove the screws holding the thermostat cover on because the combination of heat, aluminum housings, antifreeze, and steel screws can make thing difficult to remove. The screws under the injection lines are supposed to have slotted heads so that you can use a screw diver to remove them. I often find these special screws missing so I make new ones if needed.
-
Thanks Benz Dr!
-
Here's the latest. I replaced the thermostat and saw no difference in the temperature reading - still around 140F. I am confident that prior to my dash/interior refurb, the temp ran around the 180F mark. I was looking across the forum and saw in one of my prior posts on the speedo/tach cable grounds where not having this braided ground wire hooked up could influence the temperature gage. So I'm going to reinstall that ground today and see whether that makes a difference.
Otherwise, I guess I'll look at the sending unit itself. The radiator (after the engine is warmed up) is way too hot to touch but of course 140F is too hot to touch so all that tells me is that the engine is at a temperature somewhere above 120F.
Any other thoughts? I could pull the center cluster and check connections but as I recall, this was through a multi-pin connector to the cluster.
Thanks,
Harry
-
Hi, Harry,
Temp sensing thru the capillary tube is all mechanical.
No electrics involved.
Naj
-
Are you sure that you got the cooling system completely re-filled? My way is to fill through the heater inlet hose, then take the upper radiator hose loose at the radiator end, and use a funnel to add coolant to the hose until it fills, then re-connect the hose.
-
Chuck and Naj - thanks for the response. The grounding made no difference. I certainly believe that the system is full of coolant. I have driven the car many miles since I got it back on the road, including probably 200 on the highway. I would think that those speeds for that period of time would surely ensure that the system had circulated the coolant. When it cools down, I check the overflow and ensure that it is topped off. I guess I should check the capacity as well but I had expected that any air bubbles would have been worked out?
But - I simply added coolant through the overflow. Ran it till it was warmed up, let it cool and added coolant as necessary. I did not do the more involved procedure that Chuck describes.
I'll double check. Thanks very much for your assistance.
-
I hear you. But it's cheap to try. My next best suggestion is to try another thermostat. If you do that, suggest re-filling with the suggested method.
A good friend had a beautiful 280SE coupe. He had the car serviced by a dealer, including a coolant change and noted that it was running a bit cooler than before. One warm summer day, he was in line to enter a local club event. The car overheated rather spectacularly. After it cooled down, we refilled the system using my technique and no problems since.
-
The book says the 230 SL holds 2.9 gallons of coolant. That's very close to the quantity that I replaced. I have someone bringing me an infra-red gun that reads surface temperature. I think I'll take some readings on the radiator/hoses on the car when it is at running temperature. That sure give me a reasonable indication of the actual temperature - certainly good enough to determine whether it is at 140 F or 180 F. I'll re-post once I have the information.
Thanks again!
Harry
-
.../... I replaced the thermostat .../...any other thoughts?
Our six-cylinder M-B engines of the sixties are prone to forming air pockets in the cooling system after refill (like after a Thermostat exchange).
A useful practice is therefore to park the car with the nose up, like in a slope or on the ramps to a car lift. You let the engine run until it heats up, and the air will collect at the top and will be expelled (via the thin hose that goes back to the expansion tank at the firewall.
And, as has been mentioned in our Forum before, be sure to mount the thermostat with the small hole (valve) to the front, which helps the above... See picture attached
/Hans in Sweden
-
I'll check that and try the nose up position. Thanks very much. I'll be in touch.
-
I checked the temperature at the radiator and at the sending unit with the car fully warmed up, using two separate IR temperature readers and both read around 180F. The temp gage was still reading 130-140F. So the sending unit may be bad, the gage bad or possibly a bad connection. I need to read up on the sending unit to see how they convert temperature to signal. Is it resistance based? I wonder if I can check voltage at the gage, resistance at the unit?
I was thrilled the car hasn't been running cold. BTW - it's been at/below freezing on some drives. The heater is sufficient to keep you comfortable but not enough depth to have to turn it down Sound about right?
Thanks again,
Harry
-
The temperature gauge is not electrical, it is a sealed gas filled unit. Use the search function and you can find out a bunch of info on the set up. Be careful when dealing with the gauge and connection! If you knick it, it is a rebuild, that is, you can't do this one yourself.
-
Have a temp gage for sale................
-
Be careful, the temperature sending unit is filled with mercury. As the mercury expand with heat, the temperature dial rise and visa versa. If you break the line, you will spill the mercury which is poisonous. It is possible that you have a leak in the tube and the mercury level in the sender has decreased. I had to send mine for a rebuild to one of these folks advertise in the STAR magazine. I do not remember the name and contact info because it was more than 10 years ago. However, these folks still advertise in the STAR magazine. I hope this helps.
-
Thanks very much everyone. Glenn - is your gage F or C? What would you want for it if I go that route.
-
Our bud Babak at Vintage Euro Parts is selling new centigrade gauges at his eBay store for $325. I bought one and it seems to be the real deal.
CORRECTION - THIS PART DOESN'T WORK OUT OF THE BOX. SEE FOLLOW-ON POST.
Cheers,
-
The temp sender unit sits in a side pod on the left of the cylinder head.
There is a sieve-like adaptor on the head which lets water into the pod.
I wonder if the sieve is silted up not allowing enough waterflow?
Naj
-
If you send your gauge for a rebuild, it may cost you about $150. Call Palto Alto Speedometer at 650-323-0243, they might be able to fix it, if not, they will suggest someone. They are experienced in repairing MB gauges.
-
Earlier, I posted that vintageeuroparts.com was selling new gauge assemblies for $325. I was told by Babak that they would work in a 250SL. Two of us in the DC area bought these gauges. They do not work when installed in the car because the "bourdon tube" hits the side of the instrument pod, and does not allow the needle to move. My friend Ray was able to get his to work by enlarging the mounting holes enough to move the tube away from the pod's side.
The unit pictured on Babak's web site would work, but the units shipped have the bourdon tubes protruding from the right side.
Babak agreed to a refund.
Cheers,
CT
-
To clarify, the sending unit is filled with ether (don't know which one). I did some poking around the site (with the search function ) on google, and my mechanic to verify. The thing to be careful of is trying anything with flames around the tube, or potentially broken tube.
-
One other interesting thing from this exercise. One of the gauges worked, but read low. It turned out to have a kink in the tube. When the tube was straightened, it started reading normally. Decided on replacement out of concern that the kink had weakened the tube and that it would break.
-
I am about to have some time to get back to the temperature gage on my 230SL but it's behavior has me a little puzzled. As I have said before, it is functional but does not seem to reading the correct temperature. It never shows above 140F (or so) even though I have confirmed with two separate IR guns that the temperature at the engine and radiator is around 180F. The puzzling part of this is that the gage would work at all if there were a leak in the capillary or otherwise. It would seem that a leak anywhere would render the gage inoperable - there would be no corresponding pressure buildup. Does this logic stand to reason or has anyone else had experience where the gage was functional but had a leak? Curious.
Thanks,
Harry
-
Seems like your gauge is just out of calibration. It usually works or it doesn't work (no in-between). So maybe the needle on the gauge got bumped out of calibration when the dash was apart. Should be an easy fix for someone if this is the case. I think these units are filled with alcohol not mercury? When the system is accidentally cracked open all the vaporized alcohol escapes. I heard that the units are repaired by fixing the leak, re-filling the bulb with alcohol and resealing it (soldered at the bulb end), then re-calibrating the gauge. The unit is chilled while during the soldering process to keep the alcohol from turning to vapor an escaping. I am not sure that this is an accurate description of the process , but it sounds logical. Al Liefring is our resident instrument specialist. Maybe he can shed some light on this? Hey Al, are you out there?
-
Could it be that the pod where the sensor bulb fits is silted up and not allowing a full flow of the coolant
Naj
-
Please excuse me if you're seeing this post twice. It's clear that the most recent prior post was March 12. I expect that was my last post but that content isn't visible (to me) on the forum - so I will post again.
This pertains to the temperature gage that is still showing 140F with a warm engine, when I have verified through two separate IR guns that the actual temperature is 180F. The consensus seemed to be that the gage must have a leak but I question that because it would seen a leak would manifest itself with a totally inoperable gage instead of one that is partially operable. If there is a leak, how can any pressure build up? I was wondering if there has been similar experience with a temperature gage simply indicating the wrong temperature?
Thanks,
Harry
-
Harry... what do you mean that you cannot see the two replies to your original post?
-
Peter - thanks for the prompt inquiry. "Operator error" on my part. I failed to see that there were multiple pages and the first page happened to end with a post of my own. Sorry.