Head Gasket Failure Within seconds?

[datsundash]

Working on a L20B out of a 78 620, W58 open chamber round port head. The timing chain tensioner fell out so we pulled the engine to replace the timing components, as well as inspect for wear and paint the block/ re-seal etc. Got everything cleaned up and put back together. Put the engine in yesterday, started it up and within 25-30 seconds there was coolant leaking out of the head gasket right above the L20B stamp, on the passenger side of the block. The head gasket did not leak before, and the head has never been surfaced. This was a budget fix just to make things work until we can do a swap. This is why we did not resurface the head. We used a fel pro head gasket set, and we initially torqued the head bolts (re -used the old ones) to 50 ft lbs. After the leak we torqued to 61 ft lbs and it helped the leak only a little. The only variable I can imagine causing an issue would be the block head prep method we used. Normally When assembling I have a freshly machined surface but this time we used roloc surface conditioning discs. The 3m website lists them for cleaning blocks and heads, but from what I have just read they are a big NO NO. Im guessing the only way to fix this issue would be to have the head resurfaced? What are your opinions on this issue?

[I'm BLUE]

First impression ... I was going to say head/block debris issue that needs to be cleaned again.

 

BUT ... I just saw the Roloc discs portion of the reply. Off the top of my head ... if they are what I think they are ... they a big no-no in my book IMHO for head/block surfaces . I say this because people tend to go over-board with them and you see that "wavy" effect/un-even head portions when done. I was tempted to do it a long time ago , but decided not to. Will have to have it checked for flatness and more likely machined ..

 

Hell ... I don't know if the professional's use them or not ? ( if they do maybe there is a technique/touch ? might depend on the type ,,, hell IDK lol ). I sure as hell know I am not that talented though lol.

I'm afraid to use these on critical surfaces ,,, just don't trust myself ,,, :lol: ,,,

 

Take off the head again ... clean it and double check with feeler-gauge's and a GOOD straight-edge

Or just take to a machine-shop and they can check for you (likely for free) . I have a good feeling it may need to be machined now. I hope I'm wrong though. Anything's possible

 

When torqueing head-bolts ,,, hoping you did at least 3 stages of torque sequence in the correct torque pattern ...

Example = 15ft to 30ft to 50-60ft final torque (l-series varies on final ,,, I am zcar guy so I am not sure of L20b specific final )

If not done in 3 stages ^^^ that could def cause an issue right there as well

I get paranoid and do about 4-5 stages in tightening specs with bearing caps and head-gaskets lol.

 

Good luck ;)

 

Also ,,,

chase all bolt holes ,,,and clean head-bolt threads then inspect for stretch (I've seen a couple of l-series head bolts stretch ,,, pretty bad when you can see by eye lol )

make sure you have (2) block hollow dowel head guides installed in the block

Verify torque wrench is calibrated (if possible).

 

EDIT : Roloc's

 

[datzenmike]

Aluminum heads are very soft and easily grooved. If this is the case then a re surface should fix it.

Head / block surfaces must be cleaner than clean.

Head bolts need to be tightened from the center outwards to the ends in this sequence and in three steps.

 

RAD

8...7

4...3

2...1

6...5

10.9

 

Tighten in the above sequence to about 20 ft lbs. Go back and do again to 40 ft lbs. Then a final sequence to 60 ft lbs.

 

Head bolts are totally reusable but must be absolutely clean and free of rust or debris. Lightly lubed with an oily rag

 

Block bolt holes must be CLEAN. Any gasket material trapped in the bottom can prevent the bolts from reaching full clamping force on the head.

 

Put a drop of oil on each steel washer under the bolt head.

 

Check that the two block to head alignment dowels are in the block.

 

Be sure to block that timing chain so it does not fall out again. If not sure ask.

[wildmaninid]

You likely caused a dip in the surface of the head with the Roloc disc. The only Roloc style that is acceptable to clean aluminum are the ones with the many "fingers" that are soft, and they are usually green or yellow in color. If you used another style that is most likely where the problem came from.

[Drummerboy4as]

I'm having the same issue except I didn't use those discs to clean the head or the block. Just did an L20 swap with an A87 peanut head. Drove the truck to work this morning and coolant is spraying out from between the head/block right at the middle stud on the passenger side.

The one thing I didn't do is torque the head in 3 stages :/

If the coolant passages in the head were clear would it still cause coolant to spray out? Path of least resistance and all

[flatcat19]

Shitty story, Bro.

 

I've been pushing wrenches for years, and don't have a single one of those Roloc discs pictured in my tool box.

 

As Bill mentioned, the discs with the fingers are money.

I recommended the green.

Green Rolocs are what I use to do headgaskets on Nissan VQ35's.

 

Best, and only solution now is a resurface.

Did you do both the head and block?

[datsundash]

Everything was thoroughly cleaned and de-greased. I am very anal about cleaning gasket surfaces and overall engine cleanliness in general. This is the first time using the roloc discs and probably the last. I turqued to 30 ft lbs, then to 50, and then to 61, per the pattern in the FSM. Yes the alignment dowels are there, this was the first time this engine was disassemble. And yes the torque wrench is calibrated. I dont use clicker style wrenches for this reason. I only use a professional bar style wrench. All bolt holes were degreased, pressure washed, and blown out with 100psi of air to clean out any debris. I probably pressure washed the block 5 times just to be sure there wasnt any debris. I did nto resurface because there was no overheating in the past and the original headgasket did not leak. This was a budget fix only. I would say that the roloc discs damaged the head beyond spec. Im gonna pull the head. Mill it, and probably get new head bolts. I will check the block for flatness.

[datsundash]

yes both the head and block were cleaned using the roloc surface prep discs.

[datzenmike]

Probably won't hurt the block only the soft aluminum. That should fix it.

[wayno]

I only use soft wire wheels and razor blades to prep head and block surfaces, the wire wheels are for the intake/exhaust/timing chain cover/oilpan areas generally, the top of the block and bottom of head get a fresh razor blade.

One can get over zealous sanding, if something is stubborn, to much time can be spent in one spot and dig in.

I have used an orbital sander on flywheel faces/clutch cover faces without any issues, but maybe I am just lucky.

[Dirttrack510]

I've never used a disc to clean a block or a head. I alway use carb or brake cleaner to get the oil off and then I use a scraper to get the chunks, then I lightly "block sand" everything with a fine grit sand paper to make sure it's totally clean. Besides the block sanding will show you if you have any high or low spots on the head. High spots will be shinier from sanding and low spots won't shiny at all (because the sanding block won't hit em'). This should tell you if you need to resurface that head.

 

be sure to change your oil right away after doing this also, to make sure there's no SAND in you OIL. :no:

 

You can also use "copper coat" to help the gasket seal, but if your using a good FELPRO gasket, you shouldn't need it. Copper coat will not make the gasket hard to remove later, it simply helps fill in imperfections on the surfaces.

[Draker]

http://www.3m.com/product/information/Roloc-Bristle-Disc.html

 

 

This are the the roloc discs to use then doing heads or work on aluminum. Anything else is dangerous as you found out.

[wildmaninid]

Did you remove the cylinder head bolts in sequence? That can also cause a problem, though I have been wrenching for many years and never had any problem......I will bet dollars to donuts that the roloc was the issue. Just get a quick resurface and new gasket and you should be good to go!

[I'm BLUE]

Thankyou Wildmaninid and Flatcat ... for confirming Green Roloc needed for aluminum !

 

:thumbup:

 

( Now I know ,,, and If I ever needed to use it's nice to know the right shit )

[wildmaninid]

I have had the fortunate ability to be able to learn from other people's mistakes. I remember when Roloc's first came out, the 3M guy was pitching them to us. He demo'd them, then showed us some pictures of how good they work.........pictures of aluminum heads with a straightedge across them and a feeler gauge showing all of the low spots......the warning is there for a reason.

 

I use the flat razor blade method. On the block and more carefully on the cylinder head. Also, you guys should invest in some Aluma-Kleen or the like. Truckers (especially shit trucks) use it to keep the stainless and aluminum shiny. About 2 ounces per 32 oz sprayer is all you need. It is mildly acidic and cleans aluminum up very nice.

[datsundash]

Yes I used aluminum brightener on the head with great success, this is what I use to clean sr20 blocks. yes the head bolts were removed in the sequence. Everything except prepping the surfaces were done by the book, down to the letter. Like I said, this was my first time with the roloc, and it will be my last. Im gonna yank the head and chuck it in the mill.