So the two month saga is OVER... SDL BACK!!!
 

So... where do i start. And the title was chosen for a little attention grabbing effect...

A couple months ago, the inevitable finally happend. My 413K mile 86 300SDL finally really needed a head gasket. I tried a normal add in bottle of stop leak, and also the super strength stuff. Finally had the car flat bedded down to my mechanic that I have known/used for years and had him check the car out...

YUP... definitely a bad gasket...

So we arrange a price and pull the head. Bad news... slight crack and a nasty mess from a bit of bad headgasket driving, etc, etc... So, we try and find a good used head... NO LUCK! I talk to all my connections in the area, and find a good shop that can safely repair/rebuild my head.

So off to the machine shop it went, for a complete head rebuild. Two cracks fixed, all new valve guides, and one bad valve replaced. He checked the lifters and all the other parts and said that it was good as new. He had to do a lot of work to fix some of the pitting from some other crap, but when I picked it up, it looked all nice and new. I shopped around and was happy with the 895.00 out the door price that he quoted me and stuck to.

So back to the mechanic it went, and was put back together last week while I was on the east coast on vacation.

Picked up the car on Wed night (this past week) and got a couple miles from the shop and it was running warmer than I liked. So turned around and dropped it back off at the shop to have him check it the next day. I had known going into it... bad fan clutch an aux fan that would not turn on. SO... he replaced the aux fan switch with one from another car (that would fit) that comes on at a cooler temp. He also had one of his guys rebuild the fan clutch and tweak it to where it comes on sooner and tightens up faster. (I could tell since I could hear the air move as I took off from a light). I also got a new water pump, oil change, thermostat, etc. in the whole process.

So here is my question...

Before I had the problem, it would typically run 82-85C all the time. MAYBE getting up to around 90 on a warm day with the AC on.

NOW... it is running pretty much 90 all the time and this evening while driving home, it would get up to about 95-98 when I would sit at a light for a while. DID NOT go over 100 or touch 100.

IS this something I should really be concerned about OR do you think it is just a difference in the thermostat. OR... do you think that I could have plugged up the radiator with the stop leak crap to an extent that it is not able to have its max ability to cool the car down? I have a buddy who is willing to ship me his spare radiator to put in the car if I cannot get to the bottom of this slight temp increase. I am really thinkin it might be radiator... MAINLY because if i turn the heat on high, it will stay right around 80C BUT with the heat off... it runs warmer...

Give me your thoughts guys!!!

Thanks,
Aaron

well it could be.

sometimes when your car gets hot it will boil loose a lot of junk that is clinging to the inside of your motor and float it around. this stuff then gets lodged in the rad. and after fixing the reason for the hotness you still have hotness cause of the plugged cores.

did you check the fluid level? could just have a big air pocket, too.

tom w

The '86 runs at 90°C. all the time.......except when you use the boost. Even on cooler days, a reasonably heavy accel with boost will drive the temp. up closer to 100°C. It's disconcerting..........for sure........but a very long 6% upgrade at 65 mph at 75° ambient temp. failed to drive it above 105°C.

So, personally, if it can stay below 105°C, I'm not worried about it. You can go and spend a bunch of money to get a 5° improvement if you want. But, the engine won't care..........

If the heating system helps to cool the car, then the rest of the cooling system is not doing its job. In your case I suspect either the radiator or the thermostat, especially if the thermostat is new. There was a bad production run of certain brand(s) and you need to research here to find a good one and try it first, that's the easiest thing to start with.

Ken300D

if you used that copper or aluminum heavy duty stop leak
 

and did not acid flush the radiator afterwards, I will bet your radiator and probably the entire inside of the engine has gunk in it.
I have a spare parts car, so this would be a no brainer for me, but at least get the cooling system flushed really well.
John

Thanks for the advice guys...
 

I think I am going to start with the cooling system/radiator flush. I would hate to trash a very new radiator and toss a good new thermostat. I agree with Brian that I could spend tons of money to lower the temp 5-10C and not really have the motor care, but I just know what it ran at before and how my friends SDL runs at around 80-85 ALL the time. SO... I think the flush options seem best, and since it is not all over the place on the temp gauge, then I am going to assume all is good, just NOT the best flow it could have for cooling!

Thanks guys and I will keep you posted... ALSO let me know if you have any other ideas!

So here is what I found out today...
 

I first off cleaned the car cause it had been sitting for almost two months and was just looking awful. I am going to do a complete repaint later this year/fix the sunroof/and fix my rear power seat/recover my b piller covers/etc. BUT... I could not stand the car looking so neglected any longer. So after I wash and a nice coat of wax on the top surfaces, I set about to check on the engine temp issue. I started the car, and let it warm up while i waxed the top surfaces. Apply wax, let dry and buff off should give it enough time to warm up. Got into the car and with NO AC... I was running right about 2 needle marks or so above 80C. Turned the AC on, started to drive and found a few nice uphill grades, passed a old commercial truck going up a hill with the AC on, and generally gave ol Rudy a good workout. The highest the temp climbed was right about a needle mark from the 100C mark. Turned around and drove back down the hill with it still running between 90-100C. Turned on the heat full blast, and continued to drive and brought the temp back down to 80-85C. Turned off the heat and went to HIGH AC (extra load on the motor) and got it to climb back up. Pulled in to my driveway and at idle was able to keep it right about 98-100C. Usually staying a couple needle marks below 100. Heat back on HIGH... waited for the monovalve to open, and temp went back down to below 90C. Revved it up to 2500-3000 and it dropped even lower.

Here is my thought.

I tried all the easy remedies to fix the cooling system. Stop leak in the normal coolant, and then this

http://www.barsproducts.com/product.cfm?id=41

Is bars heavy duty head gasket repair. I followed the directions and flushed the cooling system, and followed the whole stupid proceedure to make sure I would get maximum results. I am thinking that somehow in this process, it plugged up the radiator a little bit and in the process of working on the motor, etc, etc. more crap got broken loose and it clogged it even further. I am guessing that my radiator is not working at 100% and might be causing the car to run at a higher temp. Especially since turning on the heat full blast seems to add enough extra cooling capacity to bring the temp back down to what I am used to. I would say the only other annoying thing that came out of this whole process was that I noticed the car being a little louder today and I looked underneath to find my coveted sound shield missing. My glorious mechanic took it off and forgot to put it back on. UGG... makes it hard to get really upset when he is a friend and is doing it as a favor at a reduced price. Oh well... I wish I would have had the time/space to do the repair myself. I know that I would have been more thorough, and would have enjoyed the whole process much like I did with another car that I had.

Again... any comments would be greatly appreciated!

Aaron

I'd try a good flush on the rad or take it to a shop to have flushed and cleaned. Is the modified fan clutch still working properly?