66 C10 sbc 400 compression issue.

[sweetlil66]

Hello guys... Thanks for your time.

I just got a 66 c10 with a sbc 400. The truck has set for over 4 years??? but it was last tagged in 03. The last owner told me when he parked it he put trans fluid in every cylinder. He also said the engine had been rebuilt not along before it was parked.

Today I rain a compression check and got 120+ on al cylinders but 2
http://basic-help.blogspot.com/2010/...-on-chevy.html
When I pulled the plugs they did smell of trans fluid.

cylinders 3 and 5 only had 65+ (When I pulled the plug from 3 there was alote gunkish mudish stuff come out but did spell of trans fluid ***I didn not smell anti freeze***) (Number 5 had a lil but not near as much)
To me this screams blown head gasket

Since 3 and 5 are next to each other -The low compression makes me think the head gasket is blown between the two cylinders.



Iv had a few guys say the valves may not be sealing properly and that I should fire it up and let it run for a half hour and then see what happens.

What worries me is what and wear did this muddish stuff come from.

Any advice?

[luvbowties]

Originally Posted by sweetlil66

Hello guys... Thanks for your time.

I just got a 66 c10 with a sbc 400. The truck has set for over 4 years??? but it was last tagged in 03. The last owner told me when he parked it he put trans fluid in every cylinder. He also said the engine had been rebuilt not along before it was parked.

Today I rain a compression check and got 120+ on al cylinders but 2
http://basic-help.blogspot.com/2010/...-on-chevy.html
When I pulled the plugs they did smell of trans fluid.

cylinders 3 and 5 only had 65+ (When I pulled the plug from 3 there was alote gunkish mudish stuff come out but did spell of trans fluid ***I didn not smell anti freeze***) (Number 5 had a lil but not near as much)
To me this screams blown head gasket

Since 3 and 5 are next to each other -The low compression makes me think the head gasket is blown between the two cylinders.



Iv had a few guys say the valves may not be sealing properly and that I should fire it up and let it run for a half hour and then see what happens.

What worries me is what and wear did this muddish stuff come from.

Any advice?

It DOES look like you could have a water-leakage problem--if so, a blown head gasket should be a welcome find! Yet, no telling what a mixture of trans fluid and remaining cylinder/piston/valve residue might look like after several years.

Please do the following, ONLY step-by-step:
Simplest 1st test is to fill rad. with water and use a pressure tester on radiator to see if pressure causes water to leak into either cylinder. If so, off come the heads--I'd never pull just that one in this scenario, even with both suspect cyls. under the same head. If no leak, continue to next parag.

You prolly already spun it over with plugs out to expel all the 'mud' you could. Drain water out of system & squirt a spoonful of engine oil in a suspect cyl. and do another comp. check, on 3 & 5. If comp. rises to good levels, chances are good the head gasket AND valves AND head are ok. Could be the rings just need 'exercising' again on those 2 cyls. If comp. fails to rise, rings are NOT the problem. To verify, continue.

Don't try starting engine yet without leaving those 2 plugs out; and try starting it on the other 6 cyls. Won't hurt engine to run JUST a bit--NOT VERY LONG--with 2 holes open to atmosphere and without water! If it starts & runs and if nothing else comes out the open holes, refill complete system with water, when cool, and let set overnite, leaving rad. cap off.

Next day, check those 2 cyl's & see if 'new' water has leaked into them, as well as inspecting level of water still in rad.

If all that looks good, you should feel safer to try running--AGAIN, NOT VERY LONG--on 8 cyl's. But, I'd re-drain water FROM ENGINE first. If it runs ok, even skipping on those 2, you should now feel safer to fill w/water when cool & re-start. It should stop skipping soon* IF rings are ok.

*I've had them run quite a few miles before skipping cyls. finally start 'hitting'.
HTH & good luck.
Sam

[sweetlil66]

Thanks luvbowties.

I havent had a chance to do to much due to that fact it been cold and rainy here.

Iv got a new issue with the truck. Iv lost power. Iv got a good battery and starter but when I hit the key it wont crank... I was messing with it yesterday and have no clue what i did but the voltage regulator started clicking and quite then i could crank on her again. Lasted about 30 mins and then back to no crank. Soo idk whats going on.

luvbowties thanks again im going to try the above asap...

Iv also got a block tester I could use...
Its like this one. http://toolsandmore.us/oem27145-bloc...FdRbPAodiRYAag


Thanks again sir.

[sweetlil66]

luvbowties i put oil in cylinder 3 today (Didn get a chance to do 5). It went from 75 to 90.
I was mistaken when i said cylinders 3 and 5 only had 65+ they wear 75+.

I did remove both spark plugs and let it set over night and there did not seem to be any thing in the cylinders the next day nor was there any drop in radiator (That i noticed)

What are the chances this is a head gasket issue and not a block cylinder wall issue?
I find it funny that there cold be two bad cylinder walls right next to each other and all the other be right at 120.

Im praying its a gasket issue. tell me something good please...



side note... I did try to fire her today. I have the tank out for cleaning so I dumped fuel in the carb and gave her a crank. She fired right up- she didn idle the best but I was able to chock the carb a little and give her some gas and she sounded alote better until the carb ran out of fuel. I test fired her a 2nd time and watched the oil psi gauge and even with low rough idle the oil psi went up to 25psi (Im using a after market gauge not the stock one) (There wear no knocks or bangs or such)


Any new advice???

[sweetlil66]

Are the firing orders the same on all sbc 400s threw out the years???

[travz500]

Originally Posted by sweetlil66

Are the firing orders the same on all sbc 400s threw out the years???

yes 18436572

[bonehead]

Sounds like a blown head gasket to me as well, and a common issue on 400's too. The bores don't have much space between them.

[DURG]

The 400 engines had a "siamese" cylinder configuration. I don't know if head gaskets are different for 400's compared to other gen 1 small blocks. If so, maybe the wrong gaskets were used? IF so, could end up with more issues in the other cylinders after some more run time.

[sweetlil66]

How would i go about finding out what gen my 400 is? Casting numbers?
Thanks for all the info guys.

[sweetlil66]

Iv also been dumping fuel down the carb to prime it could this have done it???
One thing I did notice.
When I got the truck and pulled the radiator cap = It appeared to be pure water in the radiator (This screed me ) But when I pulled the low block hose antifreeze did come out.
I was told it had a new radiator and new antifrezee and water was added (So i figured it just didn mix good bc it had not been started)

[luvbowties]

Originally Posted by sweetlil66

Iv also been dumping fuel down the carb to prime it could this have done it???
One thing I did notice.
When I got the truck and pulled the radiator cap = It appeared to be pure water in the radiator (This screed me ) But when I pulled the low block hose antifreeze did come out.
I was told it had a new radiator and new antifrezee and water was added (So i figured it just didn mix good bc it had not been started)

Change oil and filter. Bearings can't stand the looks of milky oil. Fire it back up and let it idle as suggested earlier. Stop eng. & check oil for milky-look at close intervals. If oil turns milky again, cut it off & fix the heads. Block is proly ok. No, pouring gas down carb won't turn oil milky. Luck to you!
s

[Irishbleueyes]

Originally Posted by sweetlil66

Hello guys... Thanks for your time.

I just got a 66 c10 with a sbc 400. The truck has set for over 4 years??? but it was last tagged in 03. The last owner told me when he parked it he put trans fluid in every cylinder. He also said the engine had been rebuilt not along before it was parked.

Today I rain a compression check and got 120+ on al cylinders but 2
http://basic-help.blogspot.com/2010/...-on-chevy.html
When I pulled the plugs they did smell of trans fluid.

cylinders 3 and 5 only had 65+ (When I pulled the plug from 3 there was alote gunkish mudish stuff come out but did spell of trans fluid ***I didn not smell anti freeze***) (Number 5 had a lil but not near as much)
To me this screams blown head gasket

Since 3 and 5 are next to each other -The low compression makes me think the head gasket is blown between the two cylinders.



Iv had a few guys say the valves may not be sealing properly and that I should fire it up and let it run for a half hour and then see what happens.

What worries me is what and wear did this muddish stuff come from.

Any advice?

Buy a leak down tester, about 40 bux, hook it up to a compressor. Put 3 on TDC and plug in the leak down tester. Test 5 after that and it will blow the air where the leak is, either into the water passage and cooling system or out one of the valves which you'll hear out the exhaust or carb... That will tell you exactly what the problem is.. done.. good luck man

[sweetlil66]

Can some one tell me how i can find out what gen my 400 is???
I found a cheap gasket set at summit but its only showing IT works with 70s up to 1980.
Thanks to everyone so far.

http://www.summitracing.com/parts/sl...et?prefilter=1

Make:CHEVROLET
Beginning Year:1970
Ending Year:1976
Engine Type:V8
Liter:6.6
CID:400
Engine Size:6.6L/400
Engine Family:Chevy small block Gen I
Make:CHEVROLET
Beginning Year:1975
Ending Year:1980
Engine Type:V8
Liter:6.6
CID:400
Engine Size:6.6L/400
Engine Family:Chevy small block Gen I
Application Notes:Fits truck applications.

[sweetlil66]

Can some one tell me how i can find out what gen my 400 is???
I found a cheap gasket set at summit but its only showing IT works with 70s up to 1980.
Thanks to everyone so far.

http://www.summitracing.com/parts/sl...et?prefilter=1

Make:CHEVROLET
Beginning Year:1970
Ending Year:1976
Engine Type:V8
Liter:6.6
CID:400
Engine Size:6.6L/400
Engine Family:Chevy small block Gen I
Make:CHEVROLET
Beginning Year:1975
Ending Year:1980
Engine Type:V8
Liter:6.6
CID:400
Engine Size:6.6L/400
Engine Family:Chevy small block Gen I
Application Notes:Fits truck applications.

The oil in the truck was changed a few day after getting it.

After the truck set most of the day today and all of last night - I went out and pulled the dipstick just to check what the oil looked like and to my surprise the oil looked perfect - no discoloration and it looked fresh and clean. So I fired up again ran her for 5 or 10 mins - I pulled the radiator cap to check for bubbles and there was none- I did notice VERY light white smoke coming from the tail pipe on the side with the low compression.

The other day when I first started the truck I had 25 psi on low rough idle - Today I noticed a tap on - NOT SURE WEAR but it was top side *Maybe a valve* It seemed to be around the area of the two cylinders that are low. It wasnt a bad tap but it was there - Any way I checked the oil pressure and my gauge wasnt showing oil pressure but was showing pressure a few mins before (15psi or so).
I shut her down and check the oil - and the slight milky color was back - The oil seemed thin - so thin a drop or two came off the stick (Smelled for of fuel and real watery looking - Altho it was no more milky then the day before.
(But why would it look like before running and then look milkyish after wards)?

So Im gonna do what yall said and pull the head and get new gaskets (Im thinking water or something is leaking into the block and thinning the oil out). Just to make sure Im getting a milling high volume oil pump and am gonna drop the pan clean it and install the new pump.

Ill up load pics soon!!!

Thanks guys. God bless yall. Me my wife and my 1 year old are very thankful for yalls help and advise = keep it coming. Anymore input?

[Mack B]

Originally Posted by sweetlil66

Can some one tell me how i can find out what gen my 400 is???
I found a cheap gasket set at summit but its only showing IT works with 70s up to 1980.
Thanks to everyone so far.

http://www.summitracing.com/parts/sl...et?prefilter=1

Make:CHEVROLET
Beginning Year:1970
Ending Year:1976
Engine Type:V8
Liter:6.6
CID:400
Engine Size:6.6L/400
Engine Family:Chevy small block Gen I
Make:CHEVROLET
Beginning Year:1975
Ending Year:1980
Engine Type:V8
Liter:6.6
CID:400
Engine Size:6.6L/400
Engine Family:Chevy small block Gen I
Application Notes:Fits truck applications.

Im pretty sure the 400 small black was only produced from 1970-1980, so that kit should fit your needs
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Posted via Mobile Device

['63GENIII]

Definitely pull the heads. The 400s did indeed have the siamese bores and if Im not mistaken, had heads with "steam" holes to help cooling issues that came with running the siamese bores. While you have the heads off, I would check the casting #s to be sure that you have the 400 heads. As far as block #s, look at the drivers side machined pad just in front of the head. Should be a number stamped there. Should be able to find out what it is from that. Oh yeah, I wouldnt run it anymore until ya figure out where that water is coming from.
Posted via Mobile Device
Posted via Mobile Device

[sweetlil66]

http://s1288.beta.photobucket.com/us...tml?sort=3&o=0

This is what the oil looks like after running a few mins.
The weird thing is the oil looks fine and normal before starting.

Here are other pics of the truck
http://s1288.beta.photobucket.com/us...b8bb5.jpg.html

http://s1288.beta.photobucket.com/us...610a6.jpg.html

http://s1288.beta.photobucket.com/us...a0fa0.jpg.html

http://s1288.beta.photobucket.com/us...d1ef2.jpg.html

http://s1288.beta.photobucket.com/us...9079a.jpg.html

[sweetlil66]

Thanks for the advice guys. Ill be pulling the head tomarrow I HOPE.

SOOO Its not just me right??? There is something in the oil correct?

[apachedaddy]

If the oil also smells of fuel you may have stuck rings to boot. Just food for thought...

[luvbowties]

..."The weird thing is the oil looks fine and normal before starting."...

After sitting, oil & water separate--water to bottom and oil on top.
sam

[sweetlil66]

Thanks guys. luvbowties I owe you big time -you've been there since the start of this thead.
I think Im just over analyzing everything... Deep down I know this is a head gasket issue but i cant help thinking the wrose.

I lost my dad a few weaks ago and Iv got my little brothers to take care of and my son and wife. Everything is kinda ridding on me getting this truck to run = At least long enf to get back on track.


I got the heads off today. Cylinder 3 had crud gunk all around the valves (kinda looked like some one had put Clay in the cylinder and it got compacted to the head. ( You can see between 3-5 on the gasket and the cylinder wall wear it was leaking over to each other) There does not appear to be any damage to the cylinder walls or head.

Iv ordered gaskets - new oil pump - a few other threw summit racing

[travz500]

Originally Posted by sweetlil66

Thanks guys. luvbowties I owe you big time -you've been there since the start of this thead.
I think Im just over analyzing everything... Deep down I know this is a head gasket issue but i cant help thinking the wrose.

I lost my dad a few weaks ago and Iv got my little brothers to take care of and my son and wife. Everything is kinda ridding on me getting this truck to run = At least long enf to get back on track.


I got the heads off today. Cylinder 3 had crud gunk all around the valves (kinda looked like some one had put Clay in the cylinder and it got compacted to the head. ( You can see between 3-5 on the gasket and the cylinder wall wear it was leaking over to each other) There does not appear to be any damage to the cylinder walls or head.

Iv ordered gaskets - new oil pump - a few other threw summit racing

See sometimes you get over worried when its something so simple Its probably just the gaskets but while you got the heads off run them to a machine shop and have them checked and cleaned up just some food for thought

['63GENIII]

Originally Posted by travz500

See sometimes you get over worried when its something so simple Its probably just the gaskets but while you got the heads off run them to a machine shop and have them checked and cleaned up just some food for thought

This is a good idea. Cheap insurance if you ask me. If you do take them in, have them make sure that they are for a 400 block. I think there are small differences between the 400 and the rest of the small block heads. Hang in there. You'll get it done.

[sweetlil66]

Update........ Iv got the new head gaskets installed. I was a lil confused on the torque specs for the head- I got some ppl saying 65 and 85 so i torqued her down to 80.

One thing I noticed- the edelbrock torker 3 intake has surface wear the gasket goes has issues around the front two water ports. ( not smooth ) Should I use Sealacone ? (RTV BLACK)? Should I use it on the whole gasket???? Iv got sealed power felpro gaskets.

Man woulden you know I snapped the front drive side intake bolt (Water port)
Theres enf room so I could screw a nut down on it with JB weld (Once it hardens ill try backing her out) I dont have a welder so this will have to work...
If it doesnt work Im going to trying sealing the crap out of the whole area -


I had a f150 with a 5.0 that broke like this before (Both front bolts) I was able to seal the intake with sealacon and never had a issue-I kept a 160 thermostat to keep her cooler and keep the pressure lower. - So Im praying this works again. drove her from 130k to 310k and then traded for this truck....


Im one of those ppl who believes in doing a job right -ITS A HAVE TO WITH ME.
So if i end up driving it with the broken bolt - Ill probably end of pulling the head my first pay check and getting the bolt fixed. until then ill take it easy on her.


I drained the oil today = Yep anti freeze in the oil - Ok so my worries are - did I damage the engine running her like this??? She NEVER Knocked or banged - She had oil pressure at first and then when I noticed she had almost none I shut her down.
Im pulling the pan tomorrow and installing a new oil pump = Milling high volume-
Guess I could pop a cap and take a look......


Thanks guys will keep yall posted.

[Captainfab]

There's no need tor a high volume oil pump, a stock volume will be just fine. If you have just a stock capacity oil pan (4 qts) you can suck the pan dry with a high volume oil pump at higher rpm's. And that's not a good thing.