Zipper Posted May 11, 2015 Share Posted May 11, 2015 (edited) Twice now my fan has hit the radiator during spirited driving. Ignored and repaired light damage the first time, but now my freshly repaired/painted radiator is cut pretty deep at same spot. What's the cause? Looks like a single blade on the fan moved forward at least 1/2" and hit under the tank lip - top of radiator. There's some other scars at 2-5 o'clock on face of core (looking from fan), but main strike was at the top. Pretty sure this happened when getting on RPMs (6000ish), not necessarily involving braking or maneuvers. This is an L28 in an early 260Z, OEM type radiator, I think pulley and fan clutch from 280ZX. Space to radiator always looked OK to me - runs maybe 1" from radiator, closer near the top due to radiator lip. - Weak fan drawn forward at speed - plausible - fan is old and has a couple radial cracks in front, not all the way through. - Engine mounts and torque - plausible - tranny mount is new and seems solid, engine mounts appear OK, but not sure effective test. - Fan clutch - too much resistance at RPM overwhelming fan? - Something else? I examined the engine mounts and tried various shake/pull. Seems like engine is maybe tilting forward or yawing, allowing fan to hit. I removed belt and checked water pump shaft - no apparent wobble, just a little squeak. Fresh radiator paint on one blade, traveled under the radiator lip on way up: Not great pic, but spacing looks reasonable to me - even bent, blade is approx. 1/2" from radiator tank lip, 1" from fins Blade is history - plastic stressed at base of blade Edited May 11, 2015 by Zipper Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 11, 2015 Share Posted May 11, 2015 The transmission mount is the third, rear, "engine mount". Looks like it's broke. Quote Link to comment Share on other sites More sharing options...
Zipper Posted May 11, 2015 Author Share Posted May 11, 2015 The transmission mount is the third, rear, "engine mount". Looks like it's broke. Bought a new one for the build last summer - I slid under car on ramps yesterday and gave it a shake/bench press, but didn't get much reaction. I'll take it out to see if the rubber is separated. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 11, 2015 Share Posted May 11, 2015 Another thought is that it's not the engine moving, but the radiator. Never know. Might be more effective to stick a jack under the transmission tail and see if it can lift at all. That's what would be happening. Careful on jack pressure. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted May 11, 2015 Share Posted May 11, 2015 Perhaps at higher rpm the plastic blades are getting pulled forward as a reaction to pulling in more air? Quote Link to comment Share on other sites More sharing options...
Zipper Posted May 11, 2015 Author Share Posted May 11, 2015 Perhaps at higher rpm the plastic blades are getting pulled forward as a reaction to pulling in more air? Seems possible, like maybe fan clutch too stiff, fan turning too high RPM. But I don't find complaints like this when I search Datsun sites. Quote Link to comment Share on other sites More sharing options...
Phantom Posted May 11, 2015 Share Posted May 11, 2015 Yeah, your fan clutch should be mostly disengaged by around 2500 RPM. If it's still spinning hard at higher RPM then your clutch isn't working right. The higher RPM will cause the fan to try to pull more air which will overseers the plastic and pull it toward the radiator. I'd still check out motor/transmission mounts but the fan clutch could easily be the culprit. Easy test. Rev the motor to about 4,000 RPM and hold it. The clutch should disengage and the fan should start slowing down. If it doesn't look at how much closer it is to the radiator at that speed. Quote Link to comment Share on other sites More sharing options...
The Crusher Posted May 11, 2015 Share Posted May 11, 2015 I've had the same thing happen to me, twice. New mounts, new motor, new radiator. It was my fan clutch not disengaging quick enough. I decided to go with electric fans, now all is good. Quote Link to comment Share on other sites More sharing options...
Zipper Posted May 11, 2015 Author Share Posted May 11, 2015 (edited) New motor?! OK - so fan clutch spinning too close to engine RPM. This is a replacement fan clutch (off another engine) due to earlier one not providing enough cooling, no resistance. Unfortunately, not easy to test without a radiator fix first. And at this point, I might be looking at a new radiator, considering electric, etc. More research. Don't think my alternator is stout enough for electric draw... Edited May 11, 2015 by Zipper Quote Link to comment Share on other sites More sharing options...
michael wales Posted May 12, 2015 Share Posted May 12, 2015 If the fan clutch wasn't disengaging you'd know it! Mine sounded like damn plane taking off by 4k and it happened twice and there was no missing it. I bought a generic fan electric fan kit off eBay the size of the radiator and no more worries. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 12, 2015 Share Posted May 12, 2015 If the fan's pulling itself in to the radiator you should be able to see it move while revving the engine with the hood open. If it's the engine moving, you won't see anything. Simple test, wear a face shield, or full-face helmet while experimenting. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 12, 2015 Share Posted May 12, 2015 Most likely engine mounts. Quote Link to comment Share on other sites More sharing options...
stravi757 Posted May 12, 2015 Share Posted May 12, 2015 (edited) Its 280zx fan clutch set-up. I Discovered the same problem in my brothers car after I let him use one of my aluminum radiators... The 280zx fan clutch sits to far forward. 280z style should be fine. Worn mounts wont be helping either. Edited May 12, 2015 by stravi757 Quote Link to comment Share on other sites More sharing options...
Zipper Posted May 12, 2015 Author Share Posted May 12, 2015 (edited) Thanks all for feedback. I checked the tranny mount and it's solid - not allowing more than a little forward tilt. Fan clutch seems very stiff to me though, so I think it's my main problem (aside from the gash in my radiator and broken fan). Can't test right now as I have no cooling. But I know the fan wasn't routinely roaring at higher RPMs. Its 280zx fan clutch set-up. I Discovered the same problem in my brothers car after I let him use one of my aluminum radiators... The 280zx fan clutch sits to far forward. 280z style should be fine. Worn mounts wont be helping either. I read this elsewhere, but find the water pumps and fan clutch parts seem identical for '72 - 83 Z and ZX. However, the ZX fans themselves seem to be a different design, apparently extend farther forward to clear 3-row pulley. I have two old fans, but they're the same - not sure if ZX or Z fans, so can't compare. Edited May 12, 2015 by Zipper Quote Link to comment Share on other sites More sharing options...
stravi757 Posted May 12, 2015 Share Posted May 12, 2015 (edited) Thanks all for feedback. I checked the tranny mount and it's solid - not allowing more than a little forward tilt. Fan clutch seems very stiff to me though, so I think it's my main problem (aside from the gash in my radiator and broken fan). Can't test right now as I have no cooling. But I know the fan wasn't routinely roaring at higher RPMs. I read this elsewhere, but find the water pumps and fan clutch parts seem identical for '72 - 83 Z and ZX. However, the ZX fans themselves seem to be a different design, apparently extend farther forward to clear 3-row pulley. I have two old fans, but they're the same - not sure if ZX or Z fans, so can't compare. Ah yes, I meant to write the fan blade hub. It offset is different. I see If I can find one a take a picture of both next to each other. Edited May 12, 2015 by stravi757 Quote Link to comment Share on other sites More sharing options...
Leon Posted May 12, 2015 Share Posted May 12, 2015 http://forums.hybridz.org/topic/101984-cooling-fan-for-edis-install/?p=1013878 Quote Link to comment Share on other sites More sharing options...
stravi757 Posted May 12, 2015 Share Posted May 12, 2015 (edited) http://forums.hybridz.org/topic/101984-cooling-fan-for-edis-install/?p=1013878 I take it you do not have any problems with your set-up?! Leon is that A 3 or 4 row radiator? So you can see in the link provided by Leon the difference between the two Fans. It sounds like Leon isnt having any issues. The set-up I had the problem with was using the the JWT radiator, Which I feel like would have been further away if anything compared to Leon Champion radiator. Perhaps the problem is worn mounts, maybe worn blade too. And now with that fan sitting closer with the two former things mentioned Is causing it to hit. My brothers car definitely had worn mounts at the time when we were dealing with this issue, which weren't replaced until after changing to the earlier style fan. But changing the unit to the early fan style solved the problem for us. Maybe new mounts could have prevented it too though... Good Idea to replace your mounts either if they are worn! Edited May 12, 2015 by stravi757 Quote Link to comment Share on other sites More sharing options...
Zipper Posted May 12, 2015 Author Share Posted May 12, 2015 Thanks for link Leon. Looks like you went the other way - put a ZX fan into a S30. Blade clearance looks close to me from your pics, but I didn't find your thread complaining of disaster! Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 13, 2015 Share Posted May 13, 2015 Posts #7 and #8 are the key posts in Leon's link. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 13, 2015 Share Posted May 13, 2015 Pulley and fan clutch from 280ZX won't work and there is your problem if using that same fan! Look at the assembled height of the L26 fan and clutch assembly, and of the ZX unit. It may be just the fan, the ZX having the clutch mounting surface closer to engine inside the central hub compared to the S30 configuration. Eats radiators! Quote Link to comment Share on other sites More sharing options...
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