Vacuum Pressure Question

[gunnergrant]

Just rebuilt my 2000 SOHC with the notorious timing chain issues. Reinstalled it and the exhaust headers are warped to the point they wont line up with the exhaust ports anymore, so I am having new ones installed next week.

Question is; Because my headers are disconnected, when the engine is running (No I am not driving it as is) but idling, my vacuum is really rough and bouncing around 9-10 on my boost gauge (installed because I am installing RPcaster's M112 kit when the engine is broken in). The vacuum pressure before that was about 19-20 (with blown head gaskets). Will the headers not being connected cause that much of an issue when it comes to idling and driving (I also have severe power loss)??

Please let me know so I can look for more issues I may have being that this is the first engine I rebuilt.


Specs
2000 Ford Explorer Eddie Bauer
194,700 miles before rebuild.
Ported and polished heads
Magnaflow exhaust with 2.5'' piping
K&N Cold air intake


Any input or ideas is GREATLY appreciated!!!

 

[FIND]

Yes, that is correct. When you are running your engine without the manifolds, the exhaust will not scavenge the exhaust from your combustion chamber, and therefore leave you with more leftover gasses inside your combustion chamber on the intake stroke, which means that it will pull less from the intake.

You will also have power loss, etc from running like that. Plus, you are pulling in atmosphere from the EGR instead of spent exhaust, so combustion won't be as clean or cool, which means less power too. Finally, the truck will be running in limp mode because of the exhaust not flowing over the O2 sensors and the engine's knock sensor likely being triggered from running like that.

Though, it is also possible you have a vacuum leak. You will have to diagnose that after you have everything hooked up right.

 

[gunnergrant]

Ok great. Hopefully when I get the new headers installed next week all will be fine.

Any common things that go wrong when this engine is rebuilt?

 

[pbnj22]

Ok great. Hopefully when I get the new headers installed next week all will be fine.

Any common things that go wrong when this engine is rebuilt?

yeah.. speeding tickets with the new found power!!

 

[gunnergrant]

Lmao well, plus the ported on polished heads that were added on this rebuild, I can't imagine when I bolt on the M112.....

 

[pbnj22]

going blown huh.. should have swapped in a 5.0! how much boost you going to be running? did you rebuild with forged internals!?

 

[gunnergrant]

going blown huh.. should have swapped in a 5.0! how much boost you going to be running? did you rebuild with forged internals!?

It will basically be the same exact setup as the 'Green Machine'. I have the M112 with the lightning intake and RPCaster's mounting hardware. I'm going with the stock 2.67" pulley (I think it is) and that should give me 11-13lbs.
I also will be upgrading to 42lb injectors.

And yes the only thing out of the rebuild kit I didnt use is the pistons cause I wanna put those in another engine I plan on building, that why when I blow this one up I'll have a new engine ready

 

[gunnergrant]

Ok so the manifolds just got installed professionally and it did not fix the issue...

The guy at the shop said that my head cover seals were leaking... I have vacuum reading of 10 instead of 20... im also misfiring in cylinders 1, 2 & 3....

Help! Could the leaking seals cause this? also I am going to change the plugs.

 

[2000StreetRod]

How were the camshafts timed?

Just rebuilt my 2000 SOHC with the notorious timing chain issues. . . this is the first engine I rebuilt. . .

The SOHC V6 is a complex engine for a first rebuild. What did you replace - piston rings, crankshaft and rod bearings, left & right cassettes, primary chain tensioner, etc? Was there any valve damage due to timing chain slip?

How did you time the camshafts?

Have you checked the compression on Bank 1 where the cylinders are misfiring?

 

[gunnergrant]

The SOHC V6 is a complex engine for a first rebuild. What did you replace - piston rings, crankshaft and rod bearings, left & right cassettes, primary chain tensioner, etc? Was there any valve damage due to timing chain slip?

How did you time the camshafts?

Have you checked the compression on Bank 1 where the cylinders are misfiring?

I replaced the piston rings, rod bearings, timing chains and guides. I have not yet done a compression test. I check the wiring and firing order diagrams and those are correct. I timed the cams with the cam tool set from ford for this engine.

Do you think the bank 1 cam could have slipped after I torqued down that left hand threaded bolt that holds that sprocket in?

I am going to run to the store to grab a compression test set now.

Thanks for the input, please keep it coming, school starts in 2 weeks and this is my only vehicle

 

[2000StreetRod]

was engine still running?

Was the engine still in running condition when you tore it down to replace the timing chain components? If you were driving and it suddenly died then you could have had valve damage when the timing chain slipped. If you have low compression on cylinders 1,2, & 3 then you either have incorrect timing or bent valves. The reading should be around 180 psi with the throttle wide open.

What are "head cover seals" that the mechanic told you were leaking?

 

[gunnergrant]

Yes they were in running condition when I tore it down but with blown head gaskets.

I am referring to the gasket that goes between the tops of the heads and the valve cover.

I will try to do a compression test tonight.

 

[Maniak]

Yes they were in running condition when I tore it down but with blown head gaskets.

I am referring to the gasket that goes between the tops of the heads and the valve cover.

That is typically called a valve cover gasket.

~Mark

 

[Turdle]

I don't understand how that would cause loss of vacuum.

 

[gunnergrant]

No matter what I am replacing the valve cover gaskets. I just don't know if my timing my be slightly off or I might have valve issues.

 

[2000StreetRod]

unlikely valve damage

If the engine was still running normally (except for chain rattle) when you tore it down it is unlikely that your timing chain slipped enough for the pistons to damage the valves.

If you damaged the harmonic balancer when removing or installing it so that the TDC mark was no longer accurate then both banks would have low compression and not just one - assuming that is the cause of bank 1 misfire DTCs.

Did you rotate the crankshaft any between timing the right camshaft and timing the left camshaft? Even some auto shop mechanics who are not familiar with the SOHC V6 misread the timing instructions and rotate the crankshaft 360 degrees between timing the two banks. The engine will run (but poorly) with the camshafts 180 degrees out of sync. Unfortunately, the OTC 6488 timing kit usually does not include instructions for using it. See the following thread to see if anything looks different than what you did: SOHC V6 Camshaft Timing

Did a shop test the heads for cracks before porting and polishing them?

 

[2000StreetRod]

'Green Machine'

It will basically be the same exact setup as the 'Green Machine'. I have the M112 with the lightning intake and RPCaster's mounting hardware. I'm going with the stock 2.67" pulley (I think it is) and that should give me 11-13lbs.
I also will be upgrading to 42lb injectors.

And yes the only thing out of the rebuild kit I didnt use is the pistons cause I wanna put those in another engine I plan on building, that why when I blow this one up I'll have a new engine ready

I did a Green Machine search on the forum and didn't find any posts relating to an installed M112. What is the username of Green Machine's owner? Have you picked someone for your custom tune?

 

[gunnergrant]

This is what I followed to set the timing. I used the help of one of my Spanish speaking buddies: http://www.youtube.com/watch?v=LVnG10Rpi4M

Here is the thread to the "Green Machine" http://www.explorerforum.com/forums/showthread.php?t=219092
He upgrades to the M112 on the second or third page and does a lot of other really nice work.

I am 90% sure we didnt rotate the crankshaft while setting the timing. I'm thinking now what I should do is pull of the bank 1 valve cover and flip the cam 180 degrees? Then manually rotate the crank to make sure the valves don't hit the pistons.



Thank you so much for you input thus far, it has been a great help I am very thankful for it.

 

[2000StreetRod]

the green machine

That's an excellent video on assembling the engine. I had two years of Spanish in high school fifty years ago but still remember a little. I thought I saw an adjustable wrench applied to a cam lobe to rotate the cam which I would never do.

I forgot that 4pointslow's Sport was called the Green Machine even though I've read that entire thread several times. You'll have to cut a large opening in the hood to fit the M112 blower. I recommend James Henson of Henson Performance for your custom tune. He will probably suggest you use the Deka IV 60 lb/hr injectors and a Stealth 340 fuel pump which is what I'm using. Talk with him before purchasing components.

There's no need to pull the intake to check the gross camshaft timing. A compression test should be enough.

 

[gunnergrant]

Bad news...

Compression test #1 & #4 (Two easiest to get to with a busy day), #4 gave me 80psi and #1 gave me 90psi... Weird how my misfiring one is giving me better compression....

I think I screwed up the rebuild by not having the block bored, or any of the heads machined... Yes I know, I am an idiot!!!

I think I am going to pull it and throw in a new engine, and use this one as a long term build and get parts as I can afford them, seeing that I am a college student

What would you all recommend?