wow..bad compression @ 500 miles.

[EclipticalGS]

Well, I just did a compression test today, I couldnt really get the motor up to operating temperature because I blew out the new water pump and seal driving home yesterday.

When warming the car up, im afraid that the coolant temp sensor wont know the real temp because there is barely any coolant in the system.

Car has been idling crappy at 11.2 afr.

So, I warmed up the car for about 3 minutes, until my valve cover was hot to the touch.

I did a compression test on a dsmgraveyard long block with 500 miles.

Test results cold were 110-120-90-110

Test results warm were 120-120-115-120

Test result warm with a spoonfull of oil 150-145-150-145

Why is my compression so fricken low? This is a brand new block and everything?? I did the proper breakin procedures and put load on the rings, changed the oil @ 50 miles, then 500.

So I have brand new oil in right now with about 15 miles, non-synthetic Napa 10w-30.

Let me know what I should check further??

I did have the throttle open, engine warm enough, all spark plugs out.

Thanks.

 

[1stGenTSi]

Sounds like they screwed up the ring gap or something. Have you called them yet?

 

[BogusSVO]

sounds like the rings have not took a seat yet

but you may try driving it some more and see if the rings work in.....(after you fix the cooling system leak first)

 

[EclipticalGS]

Its just depressing how sad this motor was built. But I see all these threads where people have 175 across the board @ 400-500 miles I think something is wrong here.

Any other test I can do? Leak down test maybe? Thanks

 

[BogusSVO]

was the head reworked? before installed on the short block?

a leak down test would be good to run....

also injecting compressed air thu the spark plug hole may tell you if you have a leak some where...

 

[bastarddsm]

1. What exactly was done to this motor?
2. Why would you drive it with out coolant?

 

[EclipticalGS]

I didnt drive it without coolant, the seal popped and i shut the car off on the highway, and rolled to a stop. Had the car flatbedded home. I started it while pouring water in it to let it warm up for the compression tester.

I did call them and they are going to help me, john is very nice and he said we'll get this car running again.

But i jsut wanted to ask about things I can do for this low compression? Maybe drive on it more and see if that seats the rings some more? Ive been using napa oil, any other suggestions.?

Thanks!!

 

[bastarddsm]

I didnt drive it without coolant, the seal popped and i shut the car off on the highway, and rolled to a stop. Had the car flatbedded home. I started it while pouring water in it to let it warm up for the compression tester.

I did call them and they are going to help me, john is very nice and he said we'll get this car running again.

But i jsut wanted to ask about things I can do for this low compression? Maybe drive on it more and see if that seats the rings some more? Ive been using napa oil, any other suggestions.?

Thanks!!

What was done to the block? Was it over-bored?

 

[athlete3344]

Try boosting a bit, 5-6 psi, and not balls to the wall.

It helps to seat the rings.

 

[wird06DSM]

Woah now.. IIRC Vacuum seats rings.. boost would make it worse. Correct me if Im wrong

 

[Calan]

If you've got over 500 miles on it, it's probably too late to seat the rings at this point. How did you break it in exactly?

 

[gusu]

My question is how did you drive your car?

A lot of stupid people will argue this but if you drive your new build at a consistent RPM the rings will not seat correctly and can cause all kinds of problems.

Plus you did say you were driving on the high way. You really shouldn't drive a new build on the highway.

 

[EclipticalGS]

I hit 10 psi by the time I got out of my neighborhood, I know how to break-in a motor, this is not my first.

I drive at variable rpms, switching gears, and doing WOT load pulls. in 2nd and 3rd gear.

I was on the highway switch from 3rd-4th-5th-4th-3rd-4th-5th every 20 seconds, I have been running rich at idle ever since the build, Im wondering if fuel could have washed down the walls and screwed me over.

I have in no way "babied" this motor and I have not "beat" on it. I have been doing normal 9psi break-in procedure Ive done on other motors.

Also, this test was done NOT at full operating temp. I jsut idled the motor for like 3 minutes to get some heat while pouring water into the neck.

How important is full temp during a compression test?? I had the motor warmed up to the bottom line of the coolant gauge. Just enough that valve cover was hot and the exhaust manifold was hot.

 

[athlete3344]

I would try again at full operating temp. It seems odd you have <5% difference for the cylinders. It may be that the internals are not up to operating temp even though the valve cover is hot.

 

[EclipticalGS]

Well, My coolant overflow bin had some oily, goopy brown coolant that looked black in it. Which could ahve been from my old blown motors head gasket, but im not sure.


In the first picture, I actually found a bolt underneath the valve cover !?!

2nd and third picture, what is this hole?? Is this a oil drain? I never seen them so jagged before?!

Yikes

But it should be all good, They're gettin the parts to me this week that I need the car should be up soon!!

 

[viprez586]

was the head reworked? before installed on the short block?

a leak down test would be good to run....

also injecting compressed air thu the spark plug hole may tell you if you have a leak some where...

A leak down test is injecting air into the cylinder with piston set at TDC and measuring exactly that - leak down percentage.

I would try again at full operating temp. It seems odd you have <5% difference for the cylinders. It may be that the internals are not up to operating temp even though the valve cover is hot.

5% difference is perfectly fine. Rule of thumb is 10%. Not up to operating temp wouldn't account for such low compression. Rings definitely didn't seat and running rich during break-in will not provide satisfactory results either.


Your super lucky that bolt didn't thrash up that new head. It'd certainly be hard to argue anything about a warranty.
Yes that's the oil return. Because of the casting they're jagged and rather inconsitant from head to head. Smoothing them out is a good idea to improve oil flow - returning to the pan. A lot of V8 guys do this.

 

[Calan]

WTF How does a bolt end up in the head under the VC?

It's hard to tell, but it kind of looks like a cam cap bolt. Are there any missing?

5% difference is perfectly fine. Rule of thumb is 10%. Not up to operating temp wouldn't account for such low compression. Rings definitely didn't seat and running rich during break-in will not provide satisfactory results either.

I think what athlete3344 meant was that it's odd that they are all so low, but yet that close together. Sort of points to something out of whack with the test. But I agree that if it was "warm" that it wouldn't account for them being that low.

 

[mitsubishikid]

did you get new head bolts on your build? [since they are known to streetch over time]
also were the rings gapped properly, and was the cylinders hone polished?

also were the pistons new or did you use the old ones.

 

[EclipticalGS]

This was a full engine rebuild .020 over with hot tanked block and head. Honed cylinders and brand new .020 over NPR pistons and rings, 6-bolt big rods, new crank. 6-bolt block, 7-bolt head. I talked to john (builder) and he knows the ring gaps were in spec, He checks and plastigauges all of the clearances, ARP head studs, new bearings, etc.

After I put my new water pump, oil pump, and get all my new tensioners and pulleys on and start it up. Ill let it warm up to full operating temp and do the compression again, along with a leak down test.

If my rings dont seat within another 500 miles or so, He said he'll jsut rebuild me a short block. At that time Ill just build my head up with new valves and get ready for my hx-35 I was intending to put on in a couple months.

I still cant figure out for the life of me why my car idles at 10.4-13 at idle, but I know for sure the first 50 miles of the motors life, the idle was perfect @ 14.9 all fifty short miles, and then started to idle at 14.9, but when Id take it for a drive and come back home, it would idle at 12.4 afr, then after about 100 more miles, all it does is idle at 10.4-13 I will put up a log for that problem, no CEL's or anything so idk.

Also, I drained the rest of the coolant, its still very bright green and looking good, My oil level is perfect and is still brand new oil with no milky brown look. But that gunk in my overflow i dont know where it came from?

 

[viprez586]

Sounds to me like FPR over run. Perhaps you have a faulty FPR, an injector is hanging open, etc.

 

[EclipticalGS]

Yeah im pulling the rail to powder coat or polish it so, ill check that, Any tips on how to check if that fpr is faulty?

Also what resistance should my IAC prongs have? I think thats blown too even though my car idles perfect.

 

[donniekak]

Sounds like the cylinder walls were washed out. The bolt in the head, yikes.

 

[EclipticalGS]

yeah thats what I thought too, but Ill get everything back together and run it for another couple hundred @ the right fuel trims and see if it gets any better, hopefully.

Thanks guys!!1

 

[viprez586]

Yeah im pulling the rail to powder coat or polish it so, ill check that, Any tips on how to check if that fpr is faulty?

If fuel spills out of the vacuum nipple, it cannot hold a vacuum when applied by a hand pump, and fuel pressure is whacked out of adjustment is where I would start.

Also what resistance should my IAC prongs have? I think thats blown too even though my car idles perfect.

Not off hand. Check out www.dsmisc.com I believe they have the test procedure covered.

I'd be more inclined to see if an injector is hanging open. When you remove the rail, insert all of the injectors into the rail(with fuel lines still connected of course) and make sure they fit snug(as to not pop/drop an injector out). Turn on the IGN(only) to prime the system with fuel pressure. If an injector leaks - its bad.

 

[athlete3344]

Not off hand. Check out www.dsmisc.com I believe they have the test procedure covered.

I'd be more inclined to see if an injector is hanging open. When you remove the rail, insert all of the injectors into the rail(with fuel lines still connected of course) and make sure they fit snug(as to not pop/drop an injector out). Turn on the IGN(only) to prime the system with fuel pressure. If an injector leaks - its bad.

If it were just 1 injector hanging open, do you think the compression would not be as uneven? I.E. 150-150-130-145 instead of <5 psi difference across the board?