What went wrong with the engine?

#1

So I took me SE30 to the Winterfest Enduro last week, drove 2 hours almost straight in practice on Wednesday. I put a near obscene rack of lights on the front bumper, and apparently it affected the cooling a bit. By the time I came off track and got into the paddock, the factory temp gauge was at 3/4 but the car ran fine, no issues. When on track the stock gauge was a needle over half. By way of a note, the breather on the valve cover I do not have routed into the throttle body by way of the long rubber hose, I have a rubber hose that is crudly wrapped with a rag at the end, but it has worked that way without issue for well over a year. The next morning after the Wednesday practice, we take the car out, and by lap two the car is pushing out tons of oil out of the rag that I have over the valve cover breather, and the oil looks like milkshake, so the head gasket is obviously gone (despite the fact that I changed the head and gasket just over a year ago). The car also used some water.

Today I ran a compression check. Low cylinder 153. High cylinder 167. All looks good there.

So what happened? In my experience, the only way to pressurize the crankcase is through the rings, but the rings are making good compression. On a SE30, is there some way that blowing a head gasket can pressurize the crankcase and cause the oil to come out like it did? It is clear to me that there is pressure in the crankcase. Its equally clear that the head gasket blew. Trying to decide if just pulling the head, surfacing it and putting it back together with a new head gasket will fix the issue, or whether the engine is toast.

Question 2 - what is the easy way to pull the head again, any tips or tricks? Pull it with or without the intake manifold on it? Whats the easiest way to disconnect the exhaust? Anything else that can make the job easier?

Thanks in advance.

#2

the only thing i can think of if you have milkshake is that maybe the headgasget failed into an oil passage, but I’m no where close to sure thats even a possible answer so i think you should wait for others to chime in on that one.
As for taking the head off, for ease, i always leave the manifolds on, if you are lucky your wiring harness will have a plug under the manifold that unplugs all the wiring to the head, well almost all. take the exhaust off at the manifold, hopefully it won’t be hard if you’ve ever had it off before. as for the timing belt, i can’t remember how i did it, but i think the only easy way is to take it out, unless you are comfortable unbolting the cam pulley, how i used to do it on my m10. i hope this information helps and i wish you luck with your current problem

#3

Run a leak down test. That will tell much more about the condition of the engine than a compression test.

It is possible the have a leak between a cylinder and oil return gallery, which will increase flow into the crank case, but the more likely cause would be increased blowby from the rings. If the engine was running hot, that might be a possible cause. The leak down numbers will tell.

#4

Sounds like just a head gasket. You should probably pull both manifolds if your going to have it milled. I have a puller fan and a late style cooling system so i pull the radiator anytime i need to remove the timing belt.

#5

Because the headgasket is gone it might be too late to figure out if the headgasket was the cause of the problem or a symptom. I’d do wet and dry leakdown test. The wet test is done after spurting a tablespoon of oil into the cylinder. The oil seals the rings temporarily so if the #'s suddenly improve you know you have leakage around the rings.

Lots of oil blowing out of the rocker arm cover is, as you know, classic ring problems. Another cause tho can be valve seals, but if a valve seal went I think you’d see heavy oil consumption.

Is it possible that the lights were installed such that they interfered with air flow to the radiator? Was there anything else going on that might have interfered with the engine’s cooling system and caused a HG failure from an overheat?

#6

Ranger, the lights clearly interfered with the airflow into the engine. I didn’t think it would, but it did. I just didn’t think it was that serious an issue, given that it was on track running just over halfway on the stock gauge.

I don’t even have a clue how to run leakdown, but I do own the gauge. Any clues on that?

#7

That depends on what kind of tester you have. The most common type (and the least expensive) has two gauges with an orfice in between. Once connected to a cylinder (at TDC) you adjust the regulator for a 100 reading on the supply side gauge and read the leak down percentage off the engine side gauge (that dial is calibrated backwards).

Less than 5% is god and over 15% is bad. If there is excessive leak down you can usually tell if it is the rings or valves by listening for the hiss at the oil filler opening, throttle body or exhaust.

#8

It sounds like there is cause for optimism here. That is to say the fundamental problem might have been reduced cooling air flow, that caused the aluminum head to expand too much so the HG went.

This is siginificant because it’s a scenario that could mean that the rings and head are ok.

Below is the write up on a leakdown test from my website. It goes much farther into gory details than is really necessary because I was struggling to figure out how to do the test while also struggling with a leakdown tester that didn’t work. And it wasn’t just “how to” do the test I was struggling with, but the more basic, “just how does this test work, anyhow”.

http://www.gress.org/Home/Cars/TrackTales/DIY/Leakdown%20DIY.htm

#9

On second thought, looking at your compression #'s, IMO a leakdown is a waste of time. You’ve got good compression. A leakdown is useful for helping to understand why compression is low. Your compression is not low.

Replace the HG and drive on. The boys at E30tech don’t like Victor Reinz HG’s btw. Might want to get a Goetz, instead. I think PelicanParts carries them.

#10

I wouldn’t say that leak down numbers would be a waste of time. I’ve seen engines with good compression numbers have unacceptable (for a race engine) leak down numbers. And yes, they blew a lot of oil out the valve cover vent.

#11

[quote=“Ranger” post=62928]On second thought, looking at your compression #'s, IMO a leakdown is a waste of time. You’ve got good compression. A leakdown is useful for helping to understand why compression is low. Your compression is not low.

Replace the HG and drive on. The boys at E30tech don’t like Victor Reinz HG’s btw. Might want to get a Goetz, instead. I think PelicanParts carries them.[/quote]

Thats exactly the opposite of what i’ve heard about VR vs Geotze gaskets. The turbo car destroys head gaskets without discrimination especially cometic. I’ve never had a failure on an NA motor though.

#12

Ok, so I ran leakdown numbers tonight with a Longacre gauge. Here is how I did it. Pulled the valve cover and manually cranked the engine around until compression started to form in the air line that was screwed into the spark plug opening. I could look to see that the rockers were off the springs as well. Put the car in gear, blocked the tires and put 100psi air into each cylinder. Note: The engine was cold and has not been run in days. I’m going to give the compression numbers and leakdown numbers.

  1. 168 psi 28 percent leakdown
  2. 165 psi 27 percent leakdown
  3. 170 psi 30 percent leakdown
  4. 168 psi 30 percent leakdown
  5. 163 psi 16 percent leakdown
  6. 172 psi 26 percent leakdown

Also, there was no sound of air coming out the throttle body or the exhaust, but you could feel air in the cam valley area, as if to say if the valve cover was on, you would have been able to feel air coming out where you add oil.

This test was done dry, no oil. After reading Ranger’s writeup, I will do a wet test this weekend and see if it improves. Getting the engine up to operating temperature is not a good idea because of the quantity of water in the oil.

What do we think of all that?

#13

Something isn’t right with the leakdown test. Compression test indicates things are pretty good, leakdown test is so bad that the engine might not even fire. The test protocol is bad.

#14

Gress, I thought so too, but I ran the test several times. The protocol isn’t bad I don’t think. The engine might not have been to TDC each time, but it was certainly on the compression stroke, which means the valves were all closed. There was no air coming out the exhaust or intake. As noted, the engine was cold and the test was done dry, but I think it was done right. 100psi on the inlet side each time. A seemingly good seat with the thread on the gauge, too.

#15

As far as the water in the oil, you may have cracked the head. These heads crack at the coolant passage between the rear cam journals. With the cooling system full, pressurize the cooling system to 15 psi and check that area of the head for a coolant leak.

For the bottom end, your going to have to pull the head and inspect the bore. You might also want to pull the pan and then pull a piston out for inspection.

#16

What I always hear from the pros is that compression tests are worthless and leakdown tests are what matters. Since I trust my brother and the other pros’s knowledge I’ve never done a compression test. The tester I used showed under 30% as the green and good area. Despite what your test’s say I think you should check your head for warping at the machine shop and correct it. If nothing is wrong replace your head gasket, oil and coolant.

#17

Go back and reread my web page re. leakdown tests. You can see from what I wrote just how much trouble I had figuring out how to do the test. There is no way that a properly conducted compression test can show every single cylinder fine and a properly conducted leakdown test shows every single cylinder so bad that ignition is iffy.

Compression tests aren’t bad. It’s hard to make them as reliable as a careful leakdown test tho. For example, some folks don’t account for the fact that the battery gets more tired with each test.

#18

What I always hear from the pros is that compression tests are worthless and leakdown tests are what matters. Since I trust my brother and the other pros’s knowledge I’ve never done a compression test. The tester I used showed under 30% as the green and good area. Despite what your test’s say I think you should check your head for warping at the machine shop and correct it. If nothing is wrong replace your head gasket, oil and coolant.[/quote]
A brand new terrific engine should have only a couple percentage of leakage. I’d call 5% leakage as cause for a redo on a brand new engine, or quite good for a used engine. I don’t know of any hard rule of thumb for how much leakage should trigger a rebuild, but if I had a cylinder at 10% leakage I’d use wet/dry test to figure out if it was rings or head and fix it.

I’d do the leakdown test at exactly TDC. In order to make the test as rigorous as possible you have to do the test the same way each time. In order to test it the same way, use TDC as the benchmark. Besides, cylinder wear is maximized at TDC.

#19

OK, so how do you get a cylinder exactly to TDC then?

#20

http://www.Gress.org/Home/Cars/TrackTales/DIY/ValveAdjustment.htm

I wrote this up years ago. Sadly there’s no pics. When the Cam lobes for #6 are pointing straight up, #1 is at TDC.