DaveW

You're talking about break-away torque increasing, not the tension that the bolts provide. The torque increases due to corrosion, lubricants drying out, etc. in the threads and bolt contact areas. This does not mean the the bolts have retained all of their initial tension. If the bolt tension changed at all, it would only have decreased, unless so much corrosion occurred that it started to force the bolted components apart, and that is a much different, and, certainly, not good situation.

Dave

jacobcartmill

iTrader: (6)

i think you are wrong about that one. my fourth rebuild -i think fourth- was on a motor with ~10k miles (detonated and blew a seal). i checked the torque on a few of the dowels just for the hell of it and every one i checked wasnt nearly as tight as when i had put the motor together a month or two prior.

Silverstone

That's funny. I guess I know where you get your user name
Good point but I think the hole in my engine told me that electrolysis happens and isn't good. It is a pretty well documented problem with rotary engines. But I admit it would be an interesting experiment. What would I be looking for on the meter? Seems to me it would only tell you how conductive the coolant is but we already know that anything with water in it is going to conduct. Most cars use a conductive coolant mixture containing water and then again most cars are not as prone to electrolysis damage as the RX7.

FDeez

I keep a bottle of Evans in the car with me...just in case whatever.

I also when a little nuts and added a ground cable from radiator to body in an effort to prevent electrolysis (if present). I'm not sure if that helps. But, I guess extra grounds can't hurt.

Silverstone

I want to correct something I said earlier about Evans NPG coolant. I went and looked at my containers and found that what I actually am using is the NPG+. This is Evans latest stuff which has a 32% improvement in thermal conductivity and a 65% less viscosity than regular NPG. It does contain some ethylene glycol but has some addditive to make it safer than the ethylene glycol in most standard agueous coolants. I think so highly of this coolant for high performance engines that I'm going to put it into my new Solstice GXP as well.
Here is a link for those interested: http://www.evanscooling.com/main21.htm
This is the stuff me boys. If you are as much as a freak about wanting to use the latest high performance fluids in your FD as I am, you'll want to check this out. I wanted to be sure and get this correction in because when I re-read the evans literature it specifically said that this new NPG+ can be used in every type engine that now uses standard ethylene glycol based aqueous coolants, whereas the regular NPG required modification to the cooling systems of some engines.

RotaryEvolution

iTrader: (30)

as time goes on corrosion and buildup forms on the sealing faces of the rotor housings and irons, i know breakway torque is different than rotating torque but i still do not believe retorqueing the tension bolts will save a motor.

*shrug*

as i mentioned, the seals themselves rarely fail alone, they have help from caved in iron housings.

Mahjik

iTrader: (1)

Just to clear at least one thing up; I'm not necessarily implying that it will save a motor. I'm just mentioning that people have experienced the engine bolts losing torque over time.

Whether superstition or not, those guys who do re-torque their bolts at some point of their maintenance routines and have had most less failure rates than most other FD owners. However, if they are that **** about torquing engine bolts, they are probably pretty **** about other parts of their car which also contributes to their longer lasting success.

RotaryEvolution

iTrader: (30)

you're right, it mainly is about care of the car and some luck thrown into the mix. i never would suggest to a customer that they need to pull their tranny to torque the tension bolts though, if the tranny was already off i don't have a problem with checking them.

Herblenny

iTrader: (13)

People, This debate has been covered many many times... And I have to agree with Dale. I've also heard from one of the top rotary engine builder saying that he never had an engine coolant seal fail when the engine coolant temp was below 90C... and I truely trust that builder.... His name, Rick Engman.

BLitzed33

That and they just plain flatten out over time from heat cycling and combustion and start to leak and cant hold the pressure. I bet I will have a coolant seal failure before I have a apex seal failure even with over 600 whp.

DaveW

I agree that this is the leading cause of coolant o-ring leaking, aggravated by o-ring permanent set due to heat and age.

IMO, the bolts' tension loss is a related, but relatively small, part of the coolant-seal-failure picture.

Dave

Silverstone

Ha, now I'm quoting myself. How narcissistic!

Just wanted to make the point that as the OP i was mainly concerned with *early* failure (such as mine in the 50K mi. range as opposed to the normal wear related failure in the 80K range. I think the "luck" factor mentioned by karack may really be translated into the "electrolysis" factor. Let's face it. Very few of us are the original owners of FDs. If you are one of those, you are truly a person whose love of his car must be highly respected Most of us get these things as the 3rd owner or more I suspect and we just don't know how careful the other owners were in changing their coolant on schedule. In fact I would say it is highly likely that the first owners in many cases were unintentionally negligent due to the lack of the knowlege database we now have on FDs. Mazda sure wasn't that helpful with their owners manual (states replace every 30K miles or 30 mos )

danny hahn

Alas another physical sciences lesson!

I have had some electrolysis problems on my $40ish replacement ford f150 heater core. I was going through them every two years. the $200+ OEM appeared to be aluminum, the replacement brassy colored. Now I'll tie it in to the thread.

With the cheap heater core came some instructions to measure (i think) amps across your radiator fluid to ground. They gave a threshold, my coolant failed, I brought it up with a mechanic. He showed my his test method using paper strips with a lithmus and a glycol. on his test I came out fine. however a year later the heator core was leaking.

Of course the $40 replacement is guaranteed for life so I replace it. I recall that there were some grounding straps with push on clips near the radiator connected to two adjoining body panels. I dont do anything with them. A year later heater core again.

So I ask the ford mechanics where do these straps go? they don't know as sometimes straps are there and sometimes not, so it seems to make sense to me to strap it body to radiator core as the end tanks are plastic. Its been a year and the core hasn't shown signs of leakage.

But what I learned from this and the discussion here is that I should find that amperage test threshold. For the most part I'm not one to chuck the fluid because its a year old, unless after testing I find that to be the norm.

Is anyone familiar with that fluid to ground test? or using grounding straps to limit electolysis or other methods?

I try to catch "Ship Shape" on cable whenever I can because boat owners battle this all the time. Where would one put zinc plates on the 7?

scotty305

iTrader: (2)

Google's first two results for "radiator electrolysis test":

http://www.radiatorreporter.com/electrol.html
http://www.carolinarodshop.com/Store...ectrolysis.htm


-s-

danny hahn

thanks for searching google. I skimmed throught the first article, looks like a good read. So it's a voltage test, under 0.1. I'll sit down with it make points on what to check to limit the voltage and try to figure out why certain cars shock the hell out of me. maybe I'm the ground that limits electrolysis.

My brother and I were discussing this at lunch today. He thought that I did not want my aluminum radiator core grounded whatsoever as electrolysis would take place at the point closest to ground and that aluminum he thinks would be first to be effected. We surmised that the grounding straps were probably to direct current away from certain body panels.

Now as far as the rx7, I'm hoping my aluminum radiator is installed in a manner that doesnt encourage electolysis. I've had it for 4 or 5 years. What I have noticed is deterioration under the radiator hose clamps.

Silverstone

If you are worried about electrolysis, why not switch to that waterless coolant I recommended, ya know the Evans?

danny hahn

I'm not that worried about it. Just mindful to observe and do simple test while under the hood and have the multimeter out. Particularly the next time checking coolant levels.

I hope to find a reason why I had deterioration on the radiator in/outlets under the clamps.

Silverstone

Remember for every rat you do see . . .

The deterioration you are seeing in the radiator could be happening at other places in your engine.

You make a good point about testing though.
That's the reason I started this thread. I've outlined my hypothesis and now we need some scientific measurements to support some of my conclusions. Of course all the evidence is in on the fact that FDs are just electrolysis machines more than any other car. The only question is just how much sitting does it take to eat away at the irons that hold your coolant seals in nice and tight and just how often you should change your standard coolant. It would be interesting to see what numbers you come up with and then re-measure again after you have flushed and re-filled with some Evans. Aside from the electrolysis issue, from a temperature standpoint, it seems to me that a coolant like Evans NPG+ and the FD are natural allies. FDs just run so damn hot compared to other cars as has been pointed out. I've seen reported all these fancy fixes such as changing the ECU to kick the fans on sooner etc, but perhaps all that is needed is a simple coolant switch. BTW, most of us use gauges that give us the coolant temperature only. If the coolant being use has the capacity to absorb more heat without boiling then the coolant temperature does NOT equal the engine temp. In fact you would want to see the coolant temp hotter in order to conclude that your actual engine temp is being more effectively cooled. Anyway this is all stuff that has appeared in the pros vs cons of Evans NPG+. But it should also be kept in mind that Evans newest coolant is the NPG+. The old NPG (without the +) did require modification to your cooling system and is inferior in several ways to the newer NPG+. So take another look if you haven't checked out the whole evans thing in awhile. I'm thinking that all our coolant seals would last out to the max if we had all started using a non-electrolysis, water-free coolant from the beginning. Considering the cost of replacing coolant seals, it just may be the cheapest insurance out there whether the culprit is HEAT or Electrolysis.

FDeez

From the "Radiator Reporter" article:

Umm...should I remove that ground strap I have on my radiator?

Silverstone

Yeah! And quick drain it and refill with Evans and hope that your cooling system forgives you.

danny hahn

My bad, I missed this. AC volts?

Silverstone, you are running npg+ yes? for how many months? have a multimeter? would you kindly post your volts? ac and dc? I'll try to find my multimeter.

Silverstone

I switched over to it last fall, but unfortunately I do not own a multimeter. I'll try to remember to pick one up the next time I'm in Radio Shack.

iceblue

A few things and theory adjustments in this thread still have a place. Note there are many reasons the coolant seals may fail. Some of the more common failures are due to the age of siting seals and the formation of acid based glycol in your system. As glycol ages it tends to turn into acid based fluid and eats everything away.

The larger aspect to turn to is the seals giving to overheating. The leading cause of this failure is the expansion rats of aluminum against cast. The aluminum expands quicker around double+ that of cast.

Expansion references can be found here http://bobmay.astronomy.net/misc/tempcoef.htm

When the temps climb high enough the seal is sheered of by the groove causing the seal to be pinched or sheer or compromised in some sort or fashion. As the metals cool back down the seal does not always return or is burned or is flat out missing.

The corrosion of metals has nothing to do with this directly, however has it's other pitfalls.


Lastly the tension bots undeviatingly in many cases back them selves out some and rightfully so with the expansion rate again of block and bolts themselves not to mention harmonic vibrations of the bolts. This can cause build up to increase seal failure as the sealing force against the seals is weakened. I have devised some of my own methods and tq specs to combat this issue.

FDeez

I am running Evans NPG+ with a zero pressure cap. It's been in the car for nearly two years now.

Silverstone

Yessssss! See, that's what I was talking about in my opening comments. Since the first repair I had to address within weeks of picking up my FD was an alum coolant pipe that had a hole eaten into it, I'm figuring the same process may have damaged my o-ring coolant seal. It was damaged just enough to cause some additional pressure to my cooling system but not enough to cause leakage of coolant into combustion chamber. I was able to arrest the process in time by changing the coolant as soon as I took delivery of the car. The engine is still going strong now on Evans NPG+ and changing to a 7 LB AST cap.