Landracing Forum
Tech Information => Technical Discussion => Topic started by: 38flattie on August 16, 2014, 04:46:07 PM
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The engine performed well on the dyno, but we've had issues in the car
We went to El Mirage, and thought we blew a head gasket in the pits, so we changed it.
Took the car to the salt, and again thought we had a bad head gasket, and changed it again- all to no available
I brought the car home, and did a leakdown test- most cylinders Are 0-2%, with 2 cylinders at 4% at 90 PSI- so head gaskets look good, at least with no heat in the engine.
I put a diverter in the car, to first burp the problem side- drivers side , then the passenger side. The car runs great for 3-4 minutes, then the drivers side would spike. Now, I can move the issue to the passenger side, so I thought we had an air bubble issue.
I can now burp the engine before starting, and get what appears to be all the air out. After the engine runs 3-4 minutes, I get a steady stream of air out- see 1st video.
I tried putting the caps on the system, and the car got to 210+ degrees, and the system burped air even after I shut it off.
WTF? Any ideas?https://vimeo.com/103605463 (https://vimeo.com/103605463)https://vimeo.com/103605487 (https://vimeo.com/103605487)
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Some engines trap a lot of air, on my WRX it can take a week to get all the air out unless you take special care to burp it when filling it the first time by elevating the front of the car so the air trapped in the head can get out.
Have you had someone check the air that is coming out to see if it has combustion products in it (ie exhaust).
http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm
An exhaust gas tail pipe sniffer can also detect carbon monoxide etc. In the air that is burped out as follows:
http://www.vehicleservicepros.com/article/10881931/diagnosing-engine-overheating-and-uncommon-cooling-system-problems-to-find-bad-water-pumps-had-gaskets-and-more
It might be coming from some place other than the head gasket, do you have coolant passages that are real close to pressurized intake passages (blower puffing air into the cooling system not the head gasket), or a tiny crack in an exhaust port that only passes exhaust gas under load and high temp?
Good luck on chasing this down.
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ADDED AFTER HOTROD'S POST - I think we're on the same page . . .
Couple of thoughts.
As I recall, you have a really long run to the radiator in the water tank in the back.
First thing I'd check is to see if that's air, pressure from the intake side or exhaust getting into the cooling system. The smell test would be sufficient. I believe you are running more boost than water pressure in the system, so it could still be from the intake side.
Something Mark stressed to me was that you want the highest point of the cooling system above the engine.
It's tough to get all of the air out, but if your radiator-tank sits lower than the engine, any air is going to head toward the highest point until it's forced through the system.
On a dyno, the water column is artificially made higher by the water being used in the dyno. In the car, the dynamics are all self contained.
It's a thinker - I'm just thinking at the keyboard right now.
I hate plumbing . . .
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Thanks guys!
Chris, I'm going to try and jack up the car as you suggest, and see if I can 'burp' the engine better, and see what happens!
Larry, I never knew such an animal existed, but I just returned from NAPA with the kit! If the new 'burping' method does not clear up the problem, I'll test the water and see if that tells us anything!
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Someone makes a kit to pull a vacuum on the cooling system and them it sucks coolant back into the system. You could probably fabricate one yourself that would do the same thing.
Regards, Neil Tucson, AZ
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Thanks Neil! I may need to look into that!
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Looks like to much air. And coming out to fast to be trapped air.
Richard 2
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Richard, that was my thought- what are you thinking it is?
Only thing I can think if, if it's not compression, is we either have a hotspot and are boiling the water, or somehow the intake air is getting in the water.
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Do you have cylinder sleeves?
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No sir, we do not.
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Well if there are no cracks or leaks in the Heads, Head Gaskets, Top of the Block, and no place for the boost to cross over to the coolant via a hose or super charger (and if it is getting hot quickly, I wouldn't think it would be boost pressure by its self). I guess I would be looking at the Cylinder walls. Could be a every small pin hole.
My best guess not knowing the Engine. Richard 2
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Thanks Richard! I'm going to keep looking!
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What kind of water pump are you running?
I have seen heating problems due to a water pump which had a loose impeller on the shaft, it would spin when hot and under load not pumping much water.
At low load it appeared to work just fine.
Do you have a way of monitoring your cooling system pressure?
If so does the cooling system pressure increase uniformly as it heats up or does it suddenly spike at a certain boost pressure or engine rpm/load?
Water pumps can also suck long hose sections flat under high flow, if there is a restriction (like trash caught in the line) and possibly pull air into the system on the suction side of the pump (or past its seals).
Did this start just after you had those freeze plug leaks at Speed week 2013 or one of your other events?
(just trying to maybe get a hint based on how/when it started)
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Larry, this problem started after we installed the engine I'm the car this year, after the dyno.
We blew the head gasket on the dyno, when we added 10% nitro. We took the engine home, changed the head gasket, and to the car to El Mirage. We've had issues since. At first we thought it was just a head gasket, but have replaced it 3 tomes, with no evidence of an issue there
I do not have a wY to monitor my coolant psi. This is the same setup we ran the previous year with no issue
It is a mezeire pump, and the suction side hose is only about 12" long
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Why don't you switch to an air cooled Caddy block?
You have made everything else. Make one of those !!
That makes me feel better already.
FREUD
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Freud, I'd follow your advice, but I'm afraid if I do this, then you'll want to give us fashion advice!
I'm not sure having a naked crew running around would work too well......;-)
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I could always hang out to help.
FREUD
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LOL!
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Buddy, Google Radkitplus for the vacuum filling tool sold by snap on. It's the easiest way to completely fill a system that I know. Same tool is also sold by a company called Airlift. On many late model cars it's the only way to fill them.
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Gman, thanks!!!!
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Buddy,
What was the final blow for my Street Roadster I ran at El Mirage was core shift. Motor ran fine for two seasons, then the beginning of the third season I started to get water in the oil. Then at one of the races the car did not want to start at the line, but ran fine 5 minutes earlier. Finally got it going but I swore it was hydraulic-ed. Well I tore that motor down and could not find any signs of a water leak, that is until I filled the empty block with water and pressurized it. Then I found the water leak as it dripped down from the front side of a cylinder about half way down, and it was just a drip. I have a dental tool and I put it down the cylinder where the drip was and pushed really hard and now I had a flood. The block was only .030 over. Mine did not leak until pressure built up in the radiator.
So I am wondering if you might have a port leaking air when it gets warm into the water jackets since your motor is under boost and not vacuum and in the video not under pressure build up from the radiator since the cap is not on. Just a thought.
Tom G.
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Tom, that is entirely possible. I haven't checked the oil pan, so I'll check it tomorrow. I'm just wondering if we hurt the block when we added the nitro.....
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How about pressurizing each cylinder , one at a time with air with the piston at the bottom to narrow down the search .
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NOTE - THIS IS NOT A RECOMMENDATION.
We did an experiment in junior high school where we made hydrogen through a chemical reaction.
We captured the hydrogen in a balloon.
We proved it was hydrogen by igniting it with a match on the end of a stick.
It was really cool.
In a situation such as this, if one were able to safely capture the bubbles in the cooling lines in a similar manner, one might be able to prove if it's air or an air/fuel mixture leaking into the cooling system.
Now the down-side to such an OBVIOUSLY DANGEROUS AND NON-RECOMMENDED EXPERIMENT is that if the engine spits fuel out the exhaust, typical in a high-boost engine with incomplete ignition, it's likely one would have only eliminated the possibility of air alone in the cooling system.
Of course, I would NEVER RECOMMEND SUCH A DANGEROUS, BUT REALLY COOL EXPERIMENT.
I WOULD ALSO CAUTION ANYBODY ATTEMPTING SUCH AN ILL-ADVISED TEST TO USE THE LONGEST STICK THEY COULD FIND.
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Ok, I burped this for 2.5 hours- took forever to get all of the air out. Fired it up and started getting air at 2 min. Put the cap on at 4 min and ran it 9. 5 min then ran out of fuel- temp ess 210 passenger, 195 driver- left pump running to cool engine off, but system boiled enough water out that pump quit pumping
So, is this simply a burping/ pump issue? Strange that we got air at 2 minutes even though temp was about 150- engine stated cooler lomger , but amount of air didn't change. Possible intake leak into water?
Test did not show air to be exhaust/ compression
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It sounds like you are using an electric water pump; are you absolutely certain that it is circulating the water at a decent rate? Maybe there is little or no water circulation in the heads. Water temp is measured by the instruments but not the water temp in the heads.
Regards, Neil Tucson, AZ
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Neil, At this point I'm only certain that something is very different than the past!
The pump seems to be fine, but those test are without the engine running, and no pressure. I'm looking at switching pumps, to see if this on is just old and tired, it has an intermittent issue
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Buddy, Have you done a leak down test since the Nitro?
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Yes- 6 cylinders are 0-2%, and 2 cylinders are at 4%
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leak em again, but with the pistons on the bottom of the stroke.... go slow and circulate water while you do it and watch for air....
Good luck Buddy... this one is a head n butt scratcher :|
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I don't believe you can do a leakdown on the bottom of the stroke_ I believe a valve is still open but will check it out
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Next drain the coolant and pressurize cooling system with air and listen to each cylinder, and the intake and exhaust ports (don't think so but you never know, got to rule it out) .
Some times you need to start looking at the end to find the beginning.
Richard 2
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If it is on the power stroke and before the exhaust valve opens (might have to block the crank before BDC depending on you cam timing) would work.
The other possibility is do you have a way to block off the top of the blower and pressurize the intake tract to see if you have a pin hole in an intake port or gasket leak into the coolant passages on the intake side?
You would have to prevent any of the intake valves from being open but that would eliminate one other leak path.
Other option would be to pressurize the cooling system to full system pressure and slowly jack over the engine and see if you get water in one of the cylinders or dripping out of a header pipe.
Some of the turbo guys find hidden leaks in the intake or exhaust system by pressurizing the piping with smoke.
http://www.theturboforums.com/threads/363900-DIY-smoke-machine-tester!
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Buddy;
It is not unheard of that a pump can have its impeller loose on the motor shaft or even be eaten up with corrosion. In that case, the water inside the pump housing is just being slung around inside the pump with little external flow into the engine. Can you drill & tap an 1/8" NPT fitting into the pump outlet for a pressure gauge and check that the pump is actually pressurizing the block with water?
Regards, Neil Tucson, AZ
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Neil, I have a real good Stewart Warner pump on my chiller. I have ordered an adapter, and when it comes in going to move that to the water system, along with a gauge! Thanks!
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38
I don't have anything to add re the basic problem. To help with the air bleeding problem I drilled and tapped my cylinder head at the highest point in the water jacket and put in a brake cylinder bleeder valve. It makes getting the air out of the system easier. I don't know if this is possible with your setup but I thought I would share it.
Jim
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Buddy,
How are things going? Have you found the source of the bubbles in the coolant? We need an update.
Tom G.