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replace or reuse head bolts?
02-02-2008, 04:20 PM
Post: #1
replace or reuse head bolts?
I have a question regarding a '99 Volvo S70 AWD. The engine is a 5 cylinder. It is a 2.4 ltr turbo. The head gasket was blown and the radiator and coolant reservoir filled with a slick chocolate-colored ooze. I am replacing the gasket, but was wondering if it is always necessary or recommended to also CHANGE THE BOLTS? Or is there a procedure (e.g. length measurement) to determine if existing bolts are satisfactory for reuse. ALSO, I have seen different sources conflict on recommending putting oil on the bolt threads versus putting sealant on the threads (and some oil under the head of the bolt, of course, for torquing.) What is your recommendation.
Thanks,
Joe
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02-02-2008, 09:04 PM (This post was last modified: 02-02-2008 09:08 PM by Rupe.)
Post: #2
RE: replace or reuse head bolts?
There's several schools of thought regarding replacing head bolts and the first one is obvious. If there's any rust or pitting on the shaft of the bolt then replace it. Another school says if there's a "tork to yeild" spec (so many pounds and then another partial turn) then the safe bet is replacement. Sometimes the manufacturer recommends it.

As for sealer versus lubricating threads, that depends on where the holes go. If they go into the water jacket I'd use a light coat of non-hardening sealant. If they do not go into the water jacket then a light coat of lube will generally work fine so long as there's no specific direction to NOT use any lube. (some manuals will specify clean and dry only!)

My personal preference for "light lube" is ATF or penetrating oil and lay the clean bolts on a shop towel to drain for a bit.

This is rule of thumb and personally, I do not have any specific experience with this engine. Perhaps one of the other moderators can put in their 2 cents worth.

BTW, I deleted the duplicate threads in the other sections.

Rupe
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02-03-2008, 12:59 AM
Post: #3
RE: replace or reuse head bolts?
Thanks, Rupe, for the very prompt and useful info! very helpful.

Joe
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02-03-2008, 02:46 PM
Post: #4
RE: replace or reuse head bolts?
BTW, a trick I learned many years ago for removing the slime mixture in the cooling system is to first flush with water (hot water if possible) and then refill the system with water and some automatic dishwaher detergent. Run till hot and repeate as necessary. Flush once more with clear water and then refill with 50/50 coolant mix.

The idea here is that this type of detergent is high in grease cutting agents and low in sudsing, unlike other cleansers that foam excessivly so may not reach all of the noooks and cranies.

BTW, any rubber cooling system hoses should be replaced before the final fill up as they will eventually go soft from the oil exposure.

Good luck!

Rupe
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02-03-2008, 04:55 PM
Post: #5
RE: replace or reuse head bolts?
Great tip, Rupe. That slime is EVERYWHERE and it's thick! I scooped it out from hoses and accessible passages where possible to minimize later flush sequences. I had the radiator out for easier access to the intake manifold and throttle assy - figured I might as well clean the TCM (which is problematic on this model) while I had everything apart anyway. While I had the radiator and coolant reservoir out, I used a mixture of PineSol, which is a low sudsing grease cutter as well, and fine sand, as an abrasive, and then shook the components around (the bottle was a bit easier to shake than the radiator!) to slosh the abrasive mixture back and forth. I then drained and repeated the procedure a couple of times until finally clear. Worked nicely. (BTW, I sifted the sand first to make sure there were no large particles which could lodge in the radiator fins.) Your tip will be good for flushing the rest of the system, which I had been giving some thought to. Still some sludged up components to deal with (such as the heater core which I didn't feel like removing!) At least with several major components clear, the final process should go more quickly.

Thanks for the follow-up tip, Rupe. Your comments have been very helpful. Enjoy Super Sunday!

Joe
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02-03-2008, 05:14 PM (This post was last modified: 02-03-2008 05:18 PM by Rupe.)
Post: #6
RE: replace or reuse head bolts?
The problem with using sand (or any abrasive) is it will eventually attack the water pump seal and bearings.

Do yourself a favor and flush that radiator GOOD in several directions. If you have access to compressed air just fill the radiator (laying flat) and then bubble it with the air in both directions. (the back end of a vacume cleaner will do in a pinch) Repeat till it flushes clear. Dump each flush into a clean white bucket and let it settle so you can tell if all of the sand came out.

BTW, if the slime is too thick you may need to put a garden hose into the heater core pipe to do the initial flush and then go with the dishwasher detergent.

About a half cup of Cascade or similar for each flush should do it. Take it for a ride around the block, run it through the gears and up to temp. Drain and repeat. It will probably take 3 cycles of this to make everything happy.

Oh, I believe that Pinesol amd Lestoil are both petroleum based so pay attention to replacing those rubber parts. (all hoses) The t-stat may also have a rubber seal so might as well do that too before adding the final fill of coolant. No sense in having a problem after all of that work, right?

Rupe
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02-04-2008, 04:34 AM
Post: #7
RE: replace or reuse head bolts?
Definitely understand your point, Rupe. Only added sand because I was doing those components OFF the car and no seals were being exposed. Did several power flushes afterward, monitoring the output, to be sure ALL sand was cleared (I tend to be pretty thorough in what I do.) No, I definitely wouldn't want any sand in the ENGINE and WATERPUMP circulation, and had no plans to add it then! But I had found the internals of these other parts quite resistant to releasing all their gunk with hose and air pressure only, without some type of mechanical scrubbing supplement. Especially for the radiator: once the initial pressure had cleared a few of the cooling tubes, the flow simply bypassed those remaining that were still clogged (path of least resistance) - and I didn't want to take off the end caps and rod each tube in the core indiviually. For the heater core, I did do a couple of incomplete power flushes squirting some degreaser solution into one input (no sand) and using compressed air to blow it through and then repeating from the other input (ie. outlet) direction. Got some of the gunk anyway. Your point about PineSol and rubber is well taken. Although since all the hoses were already subjected to the even more severely petroleum contaminated slime, I was planning on replacing all the hoses anyway. Funny thing is I had just done a thorough system flush and check and added new coolant only about a month ago. It's Murphy's Law - seems like just about everytime I service the cooling system on any of my (or wife's cars) and add fresh new coolant, some part of the system fails and dumps all my new coolant (and time) investment! After I finished it this time, I remember looking at the engine and thinking "ok, so what component that checks out fine now is going to be the one to blow in the next month or two this time!" I will use your Cascade idea for the full system flush once all is back together.

Thanks again,
Joe
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12-17-2009, 03:39 AM
Post: #8
RE: replace or reuse head bolts?
When tightening the head bolts remember to start with the centre bolts and work your way out both ways evenly. Never reuse old bolts, as the bolts are designed to stretch a tiny bit for a perfect fit.First tighten to 20 NM, then 60 NM and, finally, turn the bolts an additional 130 degrees.

dsi r4
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