TheSamba.com :: View topic - Diagnostic Help

Fri Jul 06, 2012 7:45 pm

Here is where I am at on my 1990 7 Passanger 2.1:

I recently replaced my high oil pressure sensor, and made the mistake of reusing a worn alt/water pump belt until I could buy a new one. Unfortunately it was too tight and broke on the way back from the store.

On the way home I heard a pop, unsure what it was, I pulled over and let it cool. When I limped home coasting down hill w/ the engine off, i went to refill the coolant reservoir in my drive and found a popped coolant distribution piece. I replaced it with a new one, and when I ran it, it was still running very hot. I decided to test the thermostat (tested ok in boiling water) and samba research uncovered the radiator bleed procedure, which I performed without issue.

Next, I discovered alot of pressure in the coolant tank (not overflow), which had a crack. I replaced this and the cap as well.

Taking it for a test, it seemed to be working well (ac cranked, driving slightly hard), but the coolant fill light would occasionally flicker. It did not overheat at all (steady at 1/2 or slightly above), but when I got it home, I decided to try to bleed if there was any more air in the radiator. Loosening the bleed screw revealed no coolant out of the screw at all, only air. I checked the overflow next it was filled to the top, and the pressure reservoir was well below the min line.

There is no liquid at all coming out of the tailpipe, the oil seems perfect, not water contaminated at all.

My next guess is either a radiator (not likely?), water pump (possible), or head gasket (cry). Any suggestions on what my next test should be.

Sat Jul 07, 2012 4:11 am

Sounds like u haven'tfully bled all the air out,sometimes takes the bleed/run a bit to get all out, don't forget to have the front heater opened upm also as it will later release some air as it refills. Of the 5 i've owned the final air bled after some driving, as long as it dont overheat and o-flo bottle don't fill up u r ok. Are u bleeding with rpms around 3K?

Sat Jul 07, 2012 8:34 am

normal. still air in there. 3k bleed n fill helps but sometimes a week of driving.

Sat Jul 07, 2012 10:10 am

Bleed the van properly and it should cure the flickering light.

Sat Jul 07, 2012 3:38 pm

I'm less concerned with the flickering light, and more concerned that the pressure in the tank seems to have forced all of the fluid into the expansion tank or out. When I bled at the end, nothing came out of the rad and the pressure coolant tank was really low.

Sat Jul 07, 2012 4:14 pm

Fill the pressure tank and allow the temperature of the coolant to heat up enuf to open the termostat.Then the pressure should force coolant/air from the rad=open all heaters full blast too

Sun Jul 08, 2012 10:14 am

I built a Libby Bong and everything seemed to go perfectly. I bled all of the air out of the rad - what an awesome idea and tool.

However, as I started running the engine, I kept watching air gurgling into the pressure tank from hose at the top of the pressure tank that connects to the plastic ring around the engine compartment (which connects to the coolant distribution connector)

There do not appear to be any leaks in the system, so I am unsure where the air could be coming from. Is this common? Any ideas?

Sun Jul 08, 2012 10:25 am

jpstewart19 wrote: I built a Libby Bong and everything seemed to go perfectly. I bled all of the air out of the rad - what an awesome idea and tool.

However, as I started running the engine, I kept watching air gurgling into the pressure tank from hose at the top of the pressure tank that connects to the plastic ring around the engine compartment (which connects to the coolant distribution connector)

There do not appear to be any leaks in the system, so I am unsure where the air could be coming from. Is this common? Any ideas?

You may well have had a failure of one of the head sealing rings. That would cause most all of your symptoms.

Sun Jul 08, 2012 1:28 pm

So I connected a pressure gauge to my old cap by cleaning out the insides and using the connector to the overflow. Cold there was no pressure at all, but slowly over about 20min it began to climb. I finally turned it off when I hit about 20psi. Now I know that there is air in the system and I want to rebleed, but is there really any reason to have 20psi in the coolant system unless a head gasket is faulty?

I tried to use a coolant exhaust tester, but once hot enough the coolant backs up, preventing me from using it properly.

Sun Jul 08, 2012 2:43 pm

jpstewart19 wrote: So I connected a pressure gauge to my old cap by cleaning out the insides and using the connector to the overflow.

Your pressure cap can not function properly when you block the relief port, so your test is pretty meaningless. If you are still getting bubbles after 20 minutes of running you have a problem, but that your pressure didn't build up all that high with the relief blocked is a good sign.

Sun Jul 08, 2012 3:37 pm

Confused - by removing the spring and guts of the old cap, it is essentially a total pass through. By connecting a pressure gauge to it, it would tell me how much pressure is in the tank. I'm not sure how this would be any different that a coolant pressure gauge, where the cap is replaced with an adapter connected to a gauge.

Definitely a bit baffled by all of this.

Sun Jul 08, 2012 5:54 pm

just put some air pressure from a air compressor into the spark plug hole it will let you know right away if you have a leak in your head gasket. i had a flickering light level and i had a small rust hole in the coolant return pipe from the water pump to thermostat housing. the hole was on the bottom side and would drip on exhaust so i would never see any leak. if you want to test the pressure in your system you need to remove the thermostat and then test this way all your hoses and pipes will have pressure.

Sun Jul 08, 2012 9:17 pm

jpstewart19 wrote: Confused - by removing the spring and guts of the old cap, it is essentially a total pass through. By connecting a pressure gauge to it, it would tell me how much pressure is in the tank. I'm not sure how this would be any different that a coolant pressure gauge, where the cap is replaced with an adapter connected to a gauge.

Definitely a bit baffled by all of this.

Sorry, I thought you were trying to check the pressure the cap was relieving at.

Your system will build pressure as it heats up, that is pretty normal, that it took so long to build up pressure is a good sign as far as a leaking head sealing ring. Are you still getting bubbles into your expansion tank?

Sun Jul 08, 2012 10:21 pm

Final Fast solution.

Beg, Borrow, Rent, Buy or Steal a pressure tester.

Get it on the expansion tank & pump it up to 15--20 lbs.

Now--sit there & watch the gauge on the pressure tester.

If it holds, your good to go.
Go up front & loosen up the bleeder & let the rest of the air outa the cooling system.

Now--if the tester dosen't hold pressure--you've got a leak.
head sealing ring, hose or something is allowing the system to lose pressure.

This is exacty why the Bong Pipe sucks man.

All it does is give you some space to fill the cooling system.

I use the pressure tester to fill Vanagon cooling system's.
It's a force fed set up--and it gets two things done at once.
If force feeds the radiator bleeder, & will let you know if you have a leak in the syetem in a heartbeat.

This will answer your guestion faster than waiting for answer's here--and you'll get the right answer the first time with pressure testing the system.

No type & wait guessing games.
Instant answer's.

This is what I would have somebody do , or you do it yourself to your Van.

Finito.

Mon Jul 09, 2012 12:20 pm

Terry - thank for the reply. I think I already did this by removing the innards of an old cap and connecting a bike pump and pressure gauge to the system. The whole thing held solid at abou 15psi for about 30 min.

My problem is as the vehicle heats up, pressure builds. When cooler, little issue. Is it possible I have a bad water pump and te pressure is the result of overheated coolant?

Mon Jul 09, 2012 8:51 pm

I'll share this one with you and you can use it as you may think is fit.

Bought a Van in Ohio.
Guy said I could drive to LA--no problem.
It was a nice Van and ran well.

However--I didn't make it to Indiana prior to blowing hoses.
I atched them & loosened the cap and made it back home.

I replaced all of the hoses--
Now that the system was tight, I'd watch the temp gauge climb as soon as I got into rush hour traffic--
I would turn on the heater's and she was OK.

And it would still drip coolant from wierd places every now & then,

The root of the problem was a plugged radiator--not all of it--just enough to build pressure internally in the cooling system.
The pump pumps one way--but isn't flowing through the raditor fast enough and causing big stem pressure.

If you know nothing about this van, and don't have an service records, I'll bet it's the radiator giving you the migrane headaches.

Good idea using the hand pump to bleed it--a lot more positive way of getting the job done rather than relying on gravity alone.

Tue Jul 24, 2012 11:10 am

Still havent solved this issue and my wife an I have been sharing a single car yikes! I hooked up a pressure gauge to my old, hollowed coolant pressure cap and it keeps creeping up. Coupling this with the bubble I keep seeing running into the pressure tank he whole time the car is running, I am concluding a head gasket. Going to buy a leak down tester today, but does anyone see any reason I am wrong at this point:

1)High pressure In coolant system creeps up to almost 18psi when I turned it off
2)No leaks when pressuring coolant system when off with pump
3) bubbles seen entering pressure tank when running
4) removed thermostat to ensure no blockages.

Tue Jul 24, 2012 11:25 am

Still havent solved this issue and my wife an I have been sharing a single car yikes! I hooked up a pressure gauge to my old, hollowed coolant pressure cap and it keeps creeping up. Coupling this with the bubble I keep seeing running into the pressure tank he whole time the car is running, I am concluding a head gasket. Going to buy a leak down tester today, but does anyone see any reason I am wrong at this point:

1)High pressure In coolant system creeps up to almost 18psi when I turned it off
2)No leaks when pressuring coolant system when off with pump
3) bubbles seen entering pressure tank when running
4) removed thermostat to ensure no blockages.

Tue Jul 24, 2012 1:33 pm

My money is on a blown headgasket and/or cracked head. Nothing else will introduce air into the system like that.

Sun Aug 05, 2012 8:22 pm

Finally received my Leak Down Tester today and gave it a whirl. After going through all cylinders, it seems that I have a definite issue with cylinder #4. The coolant started overflowing as soon as I begin to push 100 psi through the plug hole.

Oddly, when I removed the valve cover I lost about a quart of oil spilling out. I've never had this happen on my 77 West, so not sure if it means a cracked head or what.

So I'm now reading all of the advice on a head swap. It looks like I can do a drivers side swap with the engine in...fingers crossed.

For archival purposes, I originally purchased a Harbor Freight leak down tool, but it only pushes about 15psi through, which did not help diagnose the issue. I ended up replacing the right measurement gauge with a 100psi pressure gauge I had lying around, which allowed me to increase to 100psi and diagnose the issue.