Possible causes for zero compression on one side

sledgehammer357 · January 5th, 2011, 12:55 AM

I don't think the engine is blown. The mufflers were collapsed due to scraping from the former owner. I think it plugged the engine. It had new cats installed and ran for a short time. Then there were a couple loud pops and it quit running. They took the mufflers off and it runs, really erratic, but runs. It is a 4.6 DOHC. No smoke or steam from the exhaust.

rst1523 · January 5th, 2011, 04:48 PM

You might have four dead hamsters on one side.....hit up petsmart

SWEET2KSTANG · January 6th, 2011, 07:54 AM

rob had that happen on his mach and it was a broken secondary timing chain.

Uberstang1 · January 6th, 2011, 08:50 AM

You ran a compression check on all 4 cylinders on the bank and they came up zero? I would assumne if the timing chain failed you may have possible have valve damage on all 4 of those cylinders due to the pistons hitting into the valves.

32vFox · January 6th, 2011, 02:25 PM

would the timing chain fall into the oil pan or pieces of it if it broke? id say pull the oil pan.. but on these cars gotta pull the K member or the engine...or..... lift the engine high enough up to slide it off.. thats whatd id do tho

SWEET2KSTANG · January 6th, 2011, 03:28 PM

depending on how it breaks, it might or might not fall. but the timing tensioner will more than likely come apart and parts from it will fall into pan. its a lot easier to drop the k, than it is to lift and tryto get to pan.

32vFox · January 6th, 2011, 05:15 PM

agreed with sweet.. drop the k and pull the pan bro and see what u find.. might even be able to drain the oil and some might come out with it

sledgehammer357 · January 7th, 2011, 12:00 AM

I know nothing about these modular motors. The mechanics that looked at it felt that the valves were probably damaged, and pieces most likely did fall into the cylinders, causing damage. They are saying that it would be easier and safer to replace the motor, about $4k for the motor, and $1k for the labor. Thanks for the responses. Good info.

SWEET2KSTANG · January 7th, 2011, 01:42 AM

4 G's? damn, thats expensive. you can get a hell of a built engine for that. as for the valves, more than likely they are all hurt if the timing chain broke. at the same time the guides will need replaced as well. the valves will leave little dimples on the pistons, but shouldnt hurt the pistons at all.

Uberstang1 · January 7th, 2011, 07:10 AM

Originally Posted by sledgehammer357

I know nothing about these modular motors. The mechanics that looked at it felt that the valves were probably damaged, and pieces most likely did fall into the cylinders, causing damage. They are saying that it would be easier and safer to replace the motor, about $4k for the motor, and $1k for the labor. Thanks for the responses. Good info.

Did the shop have the tools avaiable to pull the plugs and run a scope into the cylinder to check for damamge or are they just guessing.

sledgehammer357 · January 9th, 2011, 12:29 AM

Just guessing. That's what made me start looking around, checking into the forum scene. I figured the car owners themselves would know best. I thought $4k for an engine was pricey, but that seems to be the average. They are running more than that on eBay for used engines. This is crazy. I just want to get the car on the road.

SWEET2KSTANG · January 9th, 2011, 01:07 AM

no way man. that price better include installation and warranty.

sledgehammer357 · January 9th, 2011, 02:10 PM

A Shop in Sacramento wanted $2k for labor alone to r & r the engine, plus $4,500 for the engine, plus any belts, hoses, fluids. If anybody out there knows of better prices, it would be appreciated.

SWEET2KSTANG · January 9th, 2011, 08:29 PM

i dont charge that, but you are quiet a distance as well.

32vFox · January 10th, 2011, 02:58 PM

man yall's shops are ripping yall a new one.. thats a hell of a price for a simple pull and replace of an engine.. id say o it yourself.. half the ppl on here could walk u thru it if u have the tools

sledgehammer357 · January 24th, 2011, 08:43 PM

I decided to do this alone. Screw the mechanics. I am having a tough time getting the valve cover off on the drivers side. Any suggestions is appreciated. I did notice that the inside chain under the cover is broken. Is that a bitch to replace? Is it doable without tearing the engine down?

32vFox · January 25th, 2011, 02:17 AM

i have a 97 cobra engine and when it was in my sn95 i had to remove the upper intake and disconnect the clutch cable from the tranny and pull it up to give more room for the valve cover to come up...

but as for the chain.. theyre pretty simple to replace... but...... its ever good when a chain breaks.. usually when that happens valves start bending and what not.. i'd do one of 2 things..
1. pull he head that the chain broke on and check out valves..

2. replace chain and do a cylinder leak down test too see if there is any loss is compression thru the valves..

na svt · January 25th, 2011, 04:37 PM

Originally Posted by sledgehammer357

I did notice that the inside chain under the cover is broken. Is that a bitch to replace? Is it doable without tearing the engine down?

If the chain is broken there will be bent valves and that will require the engine to be disassembled.

To answer your question, the chains can be replaced without tearing down the engine.

Mach Boy · January 25th, 2011, 09:20 PM

Originally Posted by SWEET2KSTANG

rob had that happen on his mach and it was a broken secondary timing chain.

Yep. It makes for a good excuse to build things bigger and better than they were before. Right?

January 5th, 2011, 12:55 AM	#1
sledgehammer357 Newbie 1999 SVT Cobra Saleen Join Date: Jan 2011 Location: Sacramento Area Posts: 20 iTrader: 0 reviews	Possible causes for zero compression on one side I don't think the engine is blown. The mufflers were collapsed due to scraping from the former owner. I think it plugged the engine. It had new cats installed and ran for a short time. Then there were a couple loud pops and it quit running. They took the mufflers off and it runs, really erratic, but runs. It is a 4.6 DOHC. No smoke or steam from the exhaust.

January 6th, 2011, 07:54 AM	#3
SWEET2KSTANG mm's nitrous mod 2000 mustang gt 11.79@115.83 (old set up) Join Date: Oct 2006 Location: N.W. AR Posts: 12,540 iTrader: 8 reviews	rob had that happen on his mach and it was a broken secondary timing chain. __________________ project warhorse under construction wagon burner under construction as well (04 lightning) being built by MP2 Performance

January 6th, 2011, 08:50 AM	#4
Uberstang1 Regular 1997 Mustang GT Join Date: Jan 2011 Location: Wilkes-Barre PA Posts: 71 iTrader: 0 reviews	You ran a compression check on all 4 cylinders on the bank and they came up zero? I would assumne if the timing chain failed you may have possible have valve damage on all 4 of those cylinders due to the pistons hitting into the valves. __________________ 97 GT, 4v swap,procharged,longtubes,tubular front suspension, team z rear suspension,4.10s moser 31s, to much to list.

January 6th, 2011, 03:28 PM	#6
SWEET2KSTANG mm's nitrous mod 2000 mustang gt 11.79@115.83 (old set up) Join Date: Oct 2006 Location: N.W. AR Posts: 12,540 iTrader: 8 reviews	depending on how it breaks, it might or might not fall. but the timing tensioner will more than likely come apart and parts from it will fall into pan. its a lot easier to drop the k, than it is to lift and tryto get to pan. __________________ project warhorse under construction wagon burner under construction as well (04 lightning) being built by MP2 Performance

January 7th, 2011, 01:42 AM	#9
SWEET2KSTANG mm's nitrous mod 2000 mustang gt 11.79@115.83 (old set up) Join Date: Oct 2006 Location: N.W. AR Posts: 12,540 iTrader: 8 reviews	4 G's? damn, thats expensive. you can get a hell of a built engine for that. as for the valves, more than likely they are all hurt if the timing chain broke. at the same time the guides will need replaced as well. the valves will leave little dimples on the pistons, but shouldnt hurt the pistons at all. __________________ project warhorse under construction wagon burner under construction as well (04 lightning) being built by MP2 Performance

January 5th, 2011, 04:48 PM	#2
rst1523 Regular 2003 Mach 1 Join Date: Jun 2010 Location: Suwanee, GA Posts: 179 iTrader: 0 reviews	You might have four dead hamsters on one side.....hit up petsmart

January 6th, 2011, 02:25 PM	#5
32vFox Regular Join Date: Jan 2011 Posts: 64 iTrader: 0 reviews	would the timing chain fall into the oil pan or pieces of it if it broke? id say pull the oil pan.. but on these cars gotta pull the K member or the engine...or..... lift the engine high enough up to slide it off.. thats whatd id do tho

January 6th, 2011, 05:15 PM	#7
32vFox Regular Join Date: Jan 2011 Posts: 64 iTrader: 0 reviews	agreed with sweet.. drop the k and pull the pan bro and see what u find.. might even be able to drain the oil and some might come out with it

January 7th, 2011, 12:00 AM	#8
sledgehammer357 Newbie 1999 SVT Cobra Saleen Join Date: Jan 2011 Location: Sacramento Area Posts: 20 iTrader: 0 reviews	I know nothing about these modular motors. The mechanics that looked at it felt that the valves were probably damaged, and pieces most likely did fall into the cylinders, causing damage. They are saying that it would be easier and safer to replace the motor, about $4k for the motor, and $1k for the labor. Thanks for the responses. Good info.

January 9th, 2011, 12:29 AM	#11
sledgehammer357 Newbie 1999 SVT Cobra Saleen Join Date: Jan 2011 Location: Sacramento Area Posts: 20 iTrader: 0 reviews	Just guessing. That's what made me start looking around, checking into the forum scene. I figured the car owners themselves would know best. I thought $4k for an engine was pricey, but that seems to be the average. They are running more than that on eBay for used engines. This is crazy. I just want to get the car on the road.

January 9th, 2011, 01:07 AM	#12
SWEET2KSTANG mm's nitrous mod 2000 mustang gt 11.79@115.83 (old set up) Join Date: Oct 2006 Location: N.W. AR Posts: 12,540 iTrader: 8 reviews	no way man. that price better include installation and warranty. __________________ project warhorse under construction wagon burner under construction as well (04 lightning) being built by MP2 Performance

January 9th, 2011, 02:10 PM	#13
sledgehammer357 Newbie 1999 SVT Cobra Saleen Join Date: Jan 2011 Location: Sacramento Area Posts: 20 iTrader: 0 reviews	A Shop in Sacramento wanted $2k for labor alone to r & r the engine, plus $4,500 for the engine, plus any belts, hoses, fluids. If anybody out there knows of better prices, it would be appreciated.

January 9th, 2011, 08:29 PM	#14
SWEET2KSTANG mm's nitrous mod 2000 mustang gt 11.79@115.83 (old set up) Join Date: Oct 2006 Location: N.W. AR Posts: 12,540 iTrader: 8 reviews	i dont charge that, but you are quiet a distance as well. __________________ project warhorse under construction wagon burner under construction as well (04 lightning) being built by MP2 Performance

January 10th, 2011, 02:58 PM	#15
32vFox Regular Join Date: Jan 2011 Posts: 64 iTrader: 0 reviews	man yall's shops are ripping yall a new one.. thats a hell of a price for a simple pull and replace of an engine.. id say o it yourself.. half the ppl on here could walk u thru it if u have the tools

January 24th, 2011, 08:43 PM	#16
sledgehammer357 Newbie 1999 SVT Cobra Saleen Join Date: Jan 2011 Location: Sacramento Area Posts: 20 iTrader: 0 reviews	I decided to do this alone. Screw the mechanics. I am having a tough time getting the valve cover off on the drivers side. Any suggestions is appreciated. I did notice that the inside chain under the cover is broken. Is that a bitch to replace? Is it doable without tearing the engine down?

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January 25th, 2011, 02:17 AM	#17
32vFox Regular Join Date: Jan 2011 Posts: 64 iTrader: 0 reviews	i have a 97 cobra engine and when it was in my sn95 i had to remove the upper intake and disconnect the clutch cable from the tranny and pull it up to give more room for the valve cover to come up... but as for the chain.. theyre pretty simple to replace... but...... its ever good when a chain breaks.. usually when that happens valves start bending and what not.. i'd do one of 2 things.. 1. pull he head that the chain broke on and check out valves.. 2. replace chain and do a cylinder leak down test too see if there is any loss is compression thru the valves..

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