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Alpha_Maverick Samba Member
Joined: May 01, 2011 Posts: 626
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Posted: Fri Apr 20, 2012 6:37 pm Post subject: Overheating 1969 1500SP... please help... I'm out of options |
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Hey, guys (and gals). I'm a long time lurker on here, and I got a new-to-me 1969 beetle in great condition last december. One major problem: I can't drive on the highway at high speed without it overheating.
When I first got it, I did an oil change (10w30, with cam-shield), and adjusted the valves, then took her out for a drive. Drove around town for a little while, just to get her warmed up, and she's a dream. I took her out on the highway, to see what she'd do, and... about four minutes later I hear detonation, and panic. She's -way- too hot, and I'm terrified that I've destroyed my lovely new car. I slow down, and get off the highway ASAP. When I slow to a stop, my oil light comes on at idle. I've been here long enough to know that I just need to keep the revs up, to help cool off the oil. I do it, and before the light at the end of the off ramp turns green, I'm doing ok again. I nurse her home, afraid to overheat again. I immediately bought a Berg-style dipstick thermometer. Now, anytime I get on the highway, she doesn't last more than three minutes before the light comes on.
Here's the setup:
It's (supposedly. I've not opened it up and measured bore/stroke) a rebuilt 1500SP. It is built around an AE case, with new cylinders and rebuilt heads. That much I can tell from the outside. It's got a 30 Pict-2 carb, and (I believe) a stock vacuum dizzy. I've set the valves at .006, the timing at TDC, dwell to 48*, and I've checked all the carb jets. I'm running a 125 main (came with a 116, I changed it), 125z air correction, and a 55 idle. I can't see any markings on the power jet, but using my twist drills to check, it's bigger than my .0250" (.635mm) but smaller than my .0280" (.7112mm). I'm not sure if it matters, but the check-ball that's supposed to be in the power circuit of the 30 PICT-2 isn't there, and I don't know what to replace it with. I've set the idle fuel pressure to 3 1/2 PSI (was over 10 when I got it). Oil cooler relief piston -was- stuck in the closed position when I got it. I've since freed the piston, but there's been no change in highway behavior with any of my changes.
All tins and seals (with the exception of a few small grommets, I'm getting to them one at a time) are in place, and all hoses are in good condition. I've installed and adjusted thermostat (new, german style) and flaps (all were missing when I bought it). They are fully open when hot, I've checked. It has a non-doghouse shroud, and the firewall insulation is in place, with all tabs secure. I'm running the stock '69 non-vented decklid.
I'm out of ideas as to what could be causing the overheating. Any help would be greatly appreciated.
TIA,
-Mav |
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Wa-hillbilly Samba Member
Joined: November 14, 2010 Posts: 65 Location: Auburn WA
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Posted: Fri Apr 20, 2012 6:51 pm Post subject: |
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have you checked your timing?very critical in a air cooled engine,is your carb running too lean............just some pointers and i am sure other people will ask you this too |
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goober Samba Member
Joined: May 03, 2003 Posts: 1183
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Posted: Fri Apr 20, 2012 8:07 pm Post subject: |
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"..about four minutes later I hear detonation, and panic."
You'll have go over the engine. Make sure that the entire cooling system is intact, tight, adjusted, free of obstructions and functioning properly.
Using Bentley, re-check all your tune-up specs, engine adjustments and systems again. If everything is there, in spec and functioning properly, you should be able to drive down the highway all day long without over heating. |
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1975 Kombi Samba Member
Joined: August 12, 2007 Posts: 2452 Location: Acton, Ontario, Canada
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Posted: Fri Apr 20, 2012 8:12 pm Post subject: |
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Oil cooler plugged maybe and how do the spark plugs look? Is the motor broken in. _________________ Brett
“He’s decieving you boy! Reach into his pocket and take what he’s got.” Mr. Crabbs.
75 Westy auto
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Pieces: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v
Last edited by 1975 Kombi on Fri Apr 20, 2012 8:40 pm; edited 1 time in total |
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Wa-hillbilly Samba Member
Joined: November 14, 2010 Posts: 65 Location: Auburn WA
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Posted: Fri Apr 20, 2012 8:36 pm Post subject: |
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you hear pinging after a short distance of running some rpms..........really sounds like your timing is off,will make her heat up fast,do you get any backfire?.............i would looks a timing posts and then check to see what disturber you have and where it should be timed at........hopefully it could be that simple[/quote] |
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69 Jim Samba Member
Joined: September 27, 2004 Posts: 6264 Location: Chickengeorge's Neighbor
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Posted: Fri Apr 20, 2012 9:19 pm Post subject: |
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Timing possibly. If the oil pressure is too high at speed, the oil cooler will be bypassed, causing overheating. |
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vw_hank Samba Member
Joined: February 07, 2001 Posts: 5371 Location: Everett WA
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Posted: Sat Apr 21, 2012 1:14 am Post subject: |
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Wa-hillbilly wrote: |
you hear pinging after a short distance of running some rpms..........really sounds like your timing is off,will make her heat up fast,do you get any backfire?.............i would looks a timing posts and then check to see what disturber you have and where it should be timed at........hopefully it could be that simple |
X10 on the timing! also are your fan shroud flaps opening? if you have A bad thermostat, "its supposed to fail safe" but if your missing the spring? _________________ 1302s sunroof..
1600cc motor. Glenn ring 010. full toplineparts.com suspension. factory front disk brakes. Tram type-3 rear brakes. Hurst shifter. empi-8's. low-back's. tons of mods! |
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morymob Samba Member
Joined: November 09, 2007 Posts: 4683 Location: east-tn
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Posted: Sat Apr 21, 2012 4:02 am Post subject: |
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Look up above pushrod tubes, is the flat tin under the center of cyls, both sides, At idle u can check if thst opens fully, i would adj so it is flaps inside housing are fully open and make a run. Could un-screw thst and manually move rod to see if flaps open /close all way freely.Agree, timing too fast will add to condition/ping. Sure it's stock and not big cyls added??Possible wrong fan, i did it long ago, picked 36 fan by mistake and almost fried a new re-build. |
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Q-Dog Samba Member
Joined: April 05, 2010 Posts: 8700 Location: Sunset, Louisiana
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Posted: Sat Apr 21, 2012 6:07 am Post subject: |
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If the heads are original 1500 heads and the engine is now a 1600, you have higher than normal compression. I don't know what was done on your rebuild, but the builder should have used spacers under the cylinders to reduce compression.
Have you tried using higher octane gas? Also try retarding the timing. _________________ Brian
'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle |
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Alpha_Maverick Samba Member
Joined: May 01, 2011 Posts: 626
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Posted: Sat Apr 21, 2012 6:41 am Post subject: |
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thanks, forgot to mention: cranking compression is about 125psi +/- 5psi between all cylinders |
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Koeppler Samba Member
Joined: April 21, 2011 Posts: 481 Location: Aging gracefully
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Posted: Sat Apr 21, 2012 7:38 am Post subject: |
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I have a very similar set up to what you have....a 1500 rebuilt as a 1600 with a 30 PICT 2, a vacuum only distributor (205M), etc. Your compression is good and your tune up #'s sound fine.
The one time I ran really hot and the oil light came on was when I forgot to tighten the distributor clamp after timing it and the distributor slipped out of time. Did you maybe do that?
Timing a vacuum only distributor at TDC statically is generally good enough but "should" be verified with a strobe. Whenever I check it with the strobe I'm usually right on or maybe a degree or so advanced. Not generally enough to cause pinging and overheating. Since you did that, you might have another issue but there's no harm in double checking the timing as that's about the simplest thing you can do.
As someone mentioned, reach above the pushrods to the bottoms of the cylinders and see if the air deflecting tin is in place there. If not, you need it. Badly b/c it serves to circulate the air along the bottoms of the cylinders. It looks like this and you'll have to pull the heads to get it on:
You mentioned your oil cooler relief being stuck. Are you sure it isn't still? It could be the case that the oil isn't getting to the cooler and is just progressively heating up. There could also be some blockage in the oiling system/oil galleys but that would involve a teardown to find.
On the somewhat simpler side but still oil related, have you checked out your oil cooler? Perhaps it's blocked or otherwise compromised?
***Edit***Also check out this thread b/c the guy's also having overheating issues but he traced them to his oiling system
http://www.thesamba.com/vw/forum/viewtopic.php?t=508149 |
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Eric&Barb Samba Member
Joined: September 19, 2004 Posts: 24764 Location: Olympia Wash Rinse & Repeat
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Posted: Sat Apr 21, 2012 4:18 pm Post subject: |
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Make sure the engine firewall insulation is not getting sucked into the fan opening.... _________________ In Stereo, Where Available! |
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Alpha_Maverick Samba Member
Joined: May 01, 2011 Posts: 626
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Posted: Sat Apr 21, 2012 4:32 pm Post subject: |
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*UPDATE*
Today, I put a tennis ball on the decklid latch, to get more air. NO real change. Later, I did an oil change with 5w20, instead of 10w30. Small change in maximum cruising speed without overheating, but not enough.
My current maximum speed at which the engine cools consistently is 65-70mph indicated (55-60 by GPS. I have slightly smaller tires on it. I'll be fixing that ASAP, once I fix the overheat)
I double checked both the oil relief piston and the firewall insulation. Piston moves freely and the insulation is quite secure, with all tabs in place and holding nicely. I also checked the oil pump. It's a 26mm. I little scored, but... from what I can tell, that's par for the course with this engine builder.
Next weekend, I'll drop the motor again, and check all the oil passages and oil cooler itself.
Thanks for the support and help so far.
ETA: -all- tins are in place. All of them. The only one that has me -slightly- concerned is the crank pulley tin that meets up with the breastplate tin. It's not exactly a precision fit between the two of them. |
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Eric&Barb Samba Member
Joined: September 19, 2004 Posts: 24764 Location: Olympia Wash Rinse & Repeat
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Posted: Sat Apr 21, 2012 5:19 pm Post subject: |
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When you pull the oil cooler, measure the inner width of the cooling fan and post result.
Oil pressure relief spring/s changed and you never know if someone could have put in any old spring or cut down the right one. So measure the spring and check out:
Too short or weak of rear spring will result in oil bypassing the cooler!
Too long or strong of rear spring will result in blown oil cooler or swelled up cooler enough to not allow the cooling air through.
How long has engine been without running??? Could be full of mouse stuff in the shroud.
Be good time to tear down to longblock for a good cleaning, filing/sawing out all casting flash in head fins, and retorque all the case and head fasteners on same sequence as if you were building it. _________________ In Stereo, Where Available! |
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scratchs68 Samba Member
Joined: May 28, 2009 Posts: 359 Location: hamilton, new jersey
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Posted: Sun Apr 22, 2012 7:33 am Post subject: |
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I'm dealing with the same issue with my car for over two years now. I just recently removed the oil cooler and pressure sending unit and used some compressed air in and blew out a large plug of shit out the hole. I'm waiting for new seals and cooler to come to try out my finding. I tried everything else, new oil pump, new pressure relief valve, timing, new plugs, new carb, exhaust wrap, new tins. I've tried everything, I'm hoping this plug was the cause for the over heating. I'm guessing the plug was causing the oil not to reach the cooler and the oil was being redirected back without cooling. Good luck. |
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priss Samba Member
Joined: May 06, 2010 Posts: 348 Location: bradford MA
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Posted: Sun Apr 22, 2012 8:50 am Post subject: |
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Alpha_Maverick wrote: |
*UPDATE*
My current maximum speed at which the engine cools consistently is 65-70mph indicated (55-60 by GPS. I have slightly smaller tires on it. I'll be fixing that ASAP, once I fix the overheat)
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The top speed of a 1969 1500 listed in the manual is what? 74ish?
Maybe..
The engine believes you are going that fast. The system is cooling the heads at the design maximum. Its a stock bug, you are getting all you are going to get. If you want to go 80-90 on the speedo, or 65-70 actual with the little tires on and expecting to solve the overheat before changing the tires then you are asking too much.
You can put as much horsepower as you want into your engine but the cooling system and heads are only going to dissipate so much. Even if you have 200hp you are only using 50ish to cruise 60mph.
3 minutes still seems really fast for an overheat tho so prolly multiple problems. Slippery fanbelt can be a problem too. _________________ I live in a state where all citizens are required to provide proof of insurance, but no person need provide proof of citizenship. |
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Greg in GA Samba Member
Joined: April 12, 2011 Posts: 436 Location: Georgia
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Posted: Sun Apr 22, 2012 8:50 am Post subject: |
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Can you see the numbers on your distributor? Please post if you can. _________________ 1969 Beetle
1974 Westy 1800cc FI conversion, L62H
Need a really good mechanic for your VW bus? Consider making an appointment with Colin (Amskeptic) next time he passes thru your area. |
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Koeppler Samba Member
Joined: April 21, 2011 Posts: 481 Location: Aging gracefully
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Posted: Sun Apr 22, 2012 10:06 am Post subject: |
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priss wrote: |
The top speed of a 1969 1500 listed in the manual is what? 74ish? |
Be nice....it's actually 78
But rebuilt as a 1600 it's what, 81? |
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Alpha_Maverick Samba Member
Joined: May 01, 2011 Posts: 626
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Posted: Sat Apr 28, 2012 2:03 pm Post subject: |
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Alright... I've pulled the engine and torn down the cooling system. Pic heavy.
First off, getting your pinkie caught between the flywheel and mounting studs hurts like the dickens, and bleeds buckets. Here's the aftermath, still leaking a little:
Next: firewall insulation. Please note that all the clips are in place and holding just fine. The insulation cannot be moved without pulling those clips.
Next: Cooling fins on engine. All clear, as far as I can tell:
Flaps (powdercoated by Awesome Powdercoat), fully open:
Fan, 28 blades, with a 5mm gap between it and the shroud:
Old pressure relief piston and spring next to the piston and spring from the "pressure booster kit" from EMPI:
I am very much tempted to put in the EMPI spring, with my old piston, as the old spring is shorter, and very much softer than the new one. I'm still trying to come up with a way to test the spring force, so I can compare it to the spec table above.
Oil cooler flows freely, and there were no blockages in the case, that I could perceive.
Distributor numbers are as follows:
JUR 4 <-
0 231 137 035
113 905 205 T |
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Alpha_Maverick Samba Member
Joined: May 01, 2011 Posts: 626
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Posted: Sat Apr 28, 2012 2:40 pm Post subject: |
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update to the update:
After doing a "best I could come up with" spring test, it looks like he put the 69 spring in the AE case. This -could- cause some serious issues... Now, do I throw the "pressure booster kit" in, or do I dig around and find OE spec springs for it? |
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