MR2 Owners Club Forum banner

41 - 60 of 85 Posts

·
Registered
Joined
·
426 Posts
Discussion Starter #41 (Edited)
It just lost power close to home and I noticed the temp go up slightly. It reached halfway on the temp as I pulled in and turned off the engine. I tried starting it and it would not start. It was spewing coolant everywhere on the right exhaust side. When I drained the oil, or should I say coolant, it was just that; coolant. So, I assumed that it was a blown head gasket.

When I took the head off, you can see where the gasket blew next to a coolant channel.

016.JPG

71682


That is on the number one cylinder which is on the right side.

Upon dismantling the motor I found that all was in good condition. There were no cracks or deformations on the head or the block. I did all the work myself. I cleaned EVERYTHING. I figured while I had it apart, I might as well do it right, and put a fresh motor in it. But, I did not have the money to have anything professionally done. I have rebuilt two of the motors in the past, and they both ran without any hickups. They were on other cars then this one.

I used a gasket kit for all of the major gaskets and seals. I bought new head bolts from Toyota (and yes, I put the washers on them during reassembly, lol). I installed new: thermostat, distributor cap and rotor, new piston rings, new spark plugs, new injectors with seals, new starter, new coolant sensor (the old one fell apart when I removed it), and a few other nit noid things. I also had to replace the injector connections. I cut them out of an old harness and sliced them as far back into the huge wiring harness as I could. I used stock for everything. The timing belt is only about 2 years old. But, I inspected it tooth by tooth, and it is good.

I checked and double-checked the cam position. The intake pin is at 12 o'clock with the mark on the pulley aligned with the matchmarks on the cover. The exhaust is at the 5 o'clock position with the matchmarks on the pulley aligned with the cover. Now, I have considered that the possibility of the crankshaft being off. But, best I can remember, I put the timing belt back on per the BGB and turned the crankshaft a few revolutions to verify alignment. I did stick a toothbrush (creative, lol) in the number one cylinder and had my son turn the crankshaft. It was at maximum height at TDC.

I have adjusted the distributor numerous times. But tonight, I went ahead and used my timing light. I assume that it should still line up correctly even though the engine is not running. It is extremely close. I did it without shorting the T and E1 connections in the service connector.

I was waiting to do a valve clearance check after I ran the motor a while and things settled in.

I forgot to mention that I put some oil in a cylinder and tried the compression check. Nothing. I can feel air coming out with my finger, but no pressure (yeah, I stuck my finger in the hole).
 

·
Registered
Joined
·
426 Posts
Discussion Starter #42 (Edited)
I am just curious. The measuring plate in the AFM is closed in a power off situation. If it doesn't open when I try to start, would that prevent adequate air from making it to the cylinders?

Update. I tried holding the plate open, and no change.
 

·
Registered
Joined
·
351 Posts
No, the AFM door won't stop air from getting into they cylinders. If it was stuck it could restrict the flow, but it couldn't stop it to where you'd have no air to move the compression tester.

I just re-read your post above. If you verified that the #1 piston was at the top of its travel when the cams are positioned as you described, and that the piston is moving up and down as you rotate the engine, then timing belt install should be fine.

The question now is, where is the air going? The piston is moving up and down, and the cams should be closing the valves at the proper time, but something is allowing the air to escape and not be compressed.

When you replaced the piston rings, did you do it with the engine in the car? Did all the ring clearances match the service manual limits?

A leakdown test would be helpful at this point. You need an air compressor and the test fixture. I don't think that's the kind of tool that the autoparts places would loan out though.

Here's a list of what I think are possible causes:
  • holes in all the pistons (unlikely)
  • cracks in all the cylinder walls or cylinder head (unlikely)
  • massively warped head or block that isn't allowing the head to compress the head gasket
  • valve are stuck open, either out of adjustment or bent
  • piston rings are completely gone
Checking the valve clearances is pretty easy. Everything else requires disassembly.
Unfortunately, it might be time to pull the head off again and start looking.
Good luck
Mike M.
 

·
Premium Member
Joined
·
12,054 Posts
It just lost power close to home and I noticed the temp go up slightly. It reached halfway on the temp as I pulled in and turned off the engine. I tried starting it and it would not start. It was spewing coolant everywhere on the right exhaust side. When I drained the oil, or should I say coolant, it was just that; coolant. So, I assumed that it was a blown head gasket.
Did you mill the head back to true before you reassembled? If not, that might explain why your new head gasket did not seal. The head gasket usually blows because the head has overheated and warped. Once the head has warped, the clamping pressure on the gasket is unbalanced, and at some time later the gasket blows out at a point where it is underclamped. If you put the warped head back on and tighten the bolts to spec, the clamping pressure imbalance is even worse than when the gasket blew the first time. Don't know if this is the situation, but I don't think that you mentioned any machine work on the head.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #45
I did some browsing on a leakdown test. I found a good vid which showed that if you remove the schrader valve in the compression tester, you can detect where the leak is. If it is blowing air out the oil cap, it's the rings (although there is always a little since the rings aren't sealed on a cold engine). If it is coming out the coolant, it is likely a head gasket. But, I kind of doubt this since my coolant has remained topped off the entire time. If it is coming out the exhaust, it is an exhaust valve(s). If it is coming out the intake, it is an intake valve(s). Fortunately, I know about schrader valves having removed them in bicycle tires.

I did not have any work done to the head other than cleaning it. I have already removed the valve covers just to check for an obvious problem with a cam shaft. Nothing. I was going to wait to do the valve clearances after putting some miles on the engine.

I'll check back in after pressurizing the cylinders, and let you know what I found. Removing the head is not a huge job, but if I can narrow down the problem I prefer to do that first.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #46
Lots of air out of the exhaust pipes on 3 out of 4 cylinders. I did not check the 4th since it is obvious. I made sure each cylinder was at TDC. Nothing from the oil cap, coolant, or intake.

I am going to remove the covers and double-triple-quaddruple check the exhaust cam position.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #47
I absolutely cannot believe it. Both of my cams are off 180 degrees. I honestly do not understand how. I checked and double-checked them. So, let me go through the timing belt replacement procedure and get back to you.
 

·
Premium Member
Joined
·
12,054 Posts
...I did not have any work done to the head other than cleaning it...
I recommend that you take it off and check it for true, and have it milled if it doesn't meet spec. Otherwise, you are likely to blow your new headgasket also. Remember that blown headgaskets are usually due to warped heads.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #49
No disrespect rmeller, I found that both my cams are 180 degrees off. I am in the process of removing the timing belt (as much as I need to to get the cams off).
 

·
Registered
Joined
·
426 Posts
Discussion Starter #50
Ah phooey. I forgot to put the number one cylinder back to TDC after checking for leaks. I remembered this last night. I'll check it tonight.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #51
Okay. Got number one at TDC. The dimples in the cams are lined up perfectly with the matchmarks on the protector. The knock pin on the intake is at 12 o'clock. The exhaust knock pin is at 5 o'clock. So, knowing that I had leakage in the exhaust, where should I start? Is it possible that all of the valves are just plain stuck open?
 

·
Registered
Joined
·
351 Posts
I'm confused. You put your cams back in the correct place, but still have zero compression on all 4 cylinders?
The 4AGE engine is not an interference design, so assuming you have stock cams, and haven't had major amount of material decked off of the head, spinning the engine with the cams in the wrong location should not damage them.

Please report you compression readings again now that you've changed the cam location.

Check your valve clearance on all 16 valves!

Keep in mind that a leakdown tester can very easily move the piston when you apply air pressure. This can cause all sorts of incorrect readings since the piston moves from TDC.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #53
I only applied 50psi to the first 3 pistons just to see if I could find out where I was loosing compression. In each case it was out the exhaust, and nowhere else.

I did recheck the cam positioning after I forgot to return number one to TDC. All good.

I am in the process of removing the head. Yeah, it sucks. But, I got a nagging feeling that for some unknown reason, some or all of my exhaust valves are stuck open. In my opinion, it is the only way to be sure.
 

·
Premium Member
Joined
·
12,054 Posts
You just have to remove the valve cover to see if your valves are in the right places. If the valve is loose, the spring will push the lifter up to the cam.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #55
I did as you recommended rmellar. I turned the exhaust camshaft and observed each of the keepers moving up and down. But, I cannot get even the skinniest checker in between the lobes and the shims on any of them. Is it possible that after cleaning everything that the valves seat further up without all of the gunk that was on them, and thus they will not close completely with the thicker shims?
 

·
Premium Member
Joined
·
12,054 Posts
If your cams never clear the lifters, then the valves never close. That is all there is to it. Why is another question, but clearly the head needs to be overhauled. I don't know what you mean by thicker shims, if you have no valve clearance as it is. A valve adjustment involves selecting shims that put the clearance at spec.

I also suggest that you get the head trued while it is apart. Deal with that first, because sometimes they are warped so badly that they cannot be salvaged. Othewise, you will just blow your next head gasket.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #57
I was referring to the shims currently in them. Having cleaned everything, I was wondering if the current shims might just simply be too thick.
 

·
Registered
Joined
·
127 Posts
Definitely worth getting the shims sorted. Any chance they were mixed up when you had the head apart? It's possible to remove the shims without pulling the cam, use a flathead to wedge the lifter down by the edge, then use a magnet to pull the shim out. Make sure the tools are very clean as this is a sensitive part of the engine.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #59
I kept the shims with the accompanying valves. Gotcha on the shim removal. I am tempted to buy some 25mm X 2.5mm shims to use in order to figure out what I need. In other words, put in the 2.5mm shim and check for the proper shim size. Make sense, lol?

In any case, I am going to remove the head and check for problems with the valves or the head itself, just to be sure.

This job has truly become a labor of love. I know that a car is simply a big piece of metal and plastic. But, this car has taken me to and from college numerous times, out to California for training, many moves, over 200k miles, and 2 marriages. Yeah, it needs a lot of TLC in addition to getting it running, but she's my girl. I really appreciate all of the advice you guys are providing. I am not perfect, and I do make mistakes. I am trying to give you guys accurate information as best that I know. I believe that despite my "going by the book," I made a mistake.
 

·
Registered
Joined
·
426 Posts
Discussion Starter #60 (Edited)
I took the cam shafts off. Upon inspection, I found one of the exhaust valve keepers "off" on the third cylinder. So, one of the exhaust valves has been "free floating." Before I completely remove the head, would this cause my problems? If so, can I simply reinstall this valve and build the head back up? Or, should I go ahead and remove the head? Reason I ask is, I dread draining the coolant in order to remove the head.

It seems to me that a clear path out the exhaust through one of the valves (imagine no valve), might cause my problem. I understand that, despite being a no interference motor, that a free floating valve doesn't count. If the valve is not bent, would simply "reattaching" it solve my problem?
 
41 - 60 of 85 Posts
Top