overheating 3.5L v8

This Landy is my first attempt at learning to turn a wrench. It's trial and error (mostly error) so go easy on me...

I got my 110 about a year ago and for the past 7-8 months I've been trying (and failing) to diagnose and fix an overheating problem. (OK, I have a newborn and a toddler - so little time to spend on the truck!) Learned lots in the process, so not a total loss... but I'd really like to get her going again 'cause the boys would love it.

Here's the list of things I've tried (some more £ than others...)
- replaced coolant
- bled air from coolant (mostly just water right now)
- replaced engine oil
- replaced thermostat
- replaced viscous fan clutch
- replaced water pump (and gasket)
- replaced expansion tank cap
- replaced belts
- forward & reverse flush of engine cooling jacket
- replaced radiator (and bottom hose)

A bit of history:
- when I bought the 110 it ran like a dog and @sypher very kindly stopped by for a day to sort it out. The biggest improvement came when he adjusted the distributor. Since we didn't have a timing light he did it by ear. It pulls fine now, but odds are good the timing is not exactly on the mark.
- after replacing the water pump the engine ran cooler (just a tad hotter than dead center) for maybe a few hundred miles, but now it's just like before
- when I first got it, the temp gauge never got past about 1/3 from the left/cold; over the course of a long (200 mile) road trip it slowly crept higher; now the gauge gets just at the top/hot end of the white after 7-8 minutes of either idling or rolling easily only the road

For overheating, the workshop manual v8 fault diagnosis section suggests a few things I definitely haven't tried: timing & oil circulation.

Still don't have a timing light. Could it be making that much difference? Perhaps it's time to get one?

As for oil circulation, I haven't the slightest idea of how to check that. Any tips would be appreciated. The oil light hasn't ever come on, but @sypher had the suspicion the pressure switch was faulty. Any tips on how to check circulation and/or test the switch gratefully received. Any straightforward way to test the oil pump?

Of course, any other ideas are much appreciated

I am in only in Whitminster if you need a hand, have a timing light

Does it boil the water?

Nick.

Mechanical oil pressure gauge sounds like head gaskets, be careful as cooking it scores oil pressure relief plunger

Thanks fanatic - I'm begrudgingly considering HGF. Sypher also suspects that's an increasingly likely candidate. I'm shopping around for a garage to do the work (I had one experience with Tim Fry and that was one too many). I'm in no rush for it (it's been 7 months already!) and I would *love* to be involved, but that's way too far above my skill level for a solo job. Anyone ever hear of a garage that would let me watch them work... I'd even consider taking off work for that.

Fanatic - were you suggesting I use a mechanical oil pressure gauge to judge oil circulation? I've been wanting to fit one for that very reason.

Nick - I last tried on Monday when it was pretty cold out. There was "steam" coming from the bleed plug opening, but I doubt it was boiling. Tbh, I don't think I've run it hot for long enough with the bleed plug off to do much boiling. Nothing like steam has ever come out of the expansion tank dump hose, either.

Oh, and I'm definitely not above accepting help. If you're feeling benevolent then I'm feeling like making a beer (or folding beer token) offering. Be warned, though, (1) I ask stupid questions and (2) the 110 won't fit in my garage so you might check the weather before making an offer

Later RV8 bolts were deleted as the heads tip @60k or so-seen several cook oil and not overheat coolant.

Sniff test would prove it

Hi....its no problem you're outside......stupid questions? all questions are good....unless you're going to be asking "Is that a Guatamarlen tree frog?" when i show you a spark plug!!!

Why do you suspect the oil pressure switch is faulty.......?

are you actually sure you have not got dodgy sender ,wiring (rubbing and making partial short )or guage ,check to feel if rad is hot all over core surface,if head gasket gone it should pump water out of expansion bottle as system becomes pressurised,are you loosing coollant ,your timing will be a bit out it does need strobe to be right but wont be the cause of your problem,neither will oil .tappets are hydraulic and will start tapping if pressure poor,

Now, I dont know a LOT about specific hgf on rv8s, but the thing is from what I've read it doesn't sound like you've actually got a problem, does it?

Does it lose/blow water? Does it emulsify the oil?

The temp guage doesnt mean anything, either the guage or sender could be out. My d1 v8 runs between just over half and 3/4 hot normally, peeps reckon that's too hot for normal. I put a HD rad in it cos it did overheat a couple times at pnp in summer (my old rad was FULL of mud it turns out) but now its absolutely spot on, 120k and never had a head gasket job. Doesnt use a spot of water or burn any oil.

So who's to say it's actually got a problem? Unless I'm missing something?

Need to get the timing right though!

Nick - I think the low-pressure switch might be faulty because, when sypher stopped by, the oil was low, but the light wasn't on. He shorted a wire near the switch to check the dash warning light worked (it did) and suggested it might be worth putting in a new switch.

James - I haven't ruled out the temp sender, wiring, or gauge. It's something I'd like to check, but don't really know how (or where the sender is, for a start).

Once is a while I see a little coolant pooling on top of the engine, between (what I think are) the rocker covers. Never been able to find a source, though.

If you get a pool on top it could be making from head gasket, water pump/front casing, throttle body, etc.

If it's not spraying out though its not worth worrying about!

Temp sender is on drivers side front cylinder head area iirc, it looks like the oil sender but smaller version. I've had to replace mine a few times.

Would be interesting to fit a proper temp guage into the top hose and compare with other peeps/book data - just to determine if it is actually hot...

please check rad by touch ,sender should be behind water pump on inlet manifold ,which sits between heads inlet manifold has coolant going through it, and small leaks on valley gasket are not uncommon

James - checking temp by touch..

Just before ordering a new rad, I felt rad for temp. It was hotat the top 1/3 and cold across the bottom 1/3, with an even gradient across the middle 1/3. The inconsistency was my biggest reason for ordering a new one - although it was apparently unnecessary. :doh:

After putting in the new rad, I haven't felt the rad itself with engine running, but I have felt the hoses. The top hose (coolant from engine to rad) is *definitely* warm. The hose was hotter than I ever remember it being before, but it was running mostly water for coolant, so perhaps that might explain it?

Noisy - You're right in that, other than the temp gauge, I haven't noticed any other problems. I'd feel properly stupid if it was the sender this whole time, but at least I'd know. Is this the sender? Looks easy enough to do.

Can't enlarge the pic on my phone mate, but yeah It looks very much like the right area!!

Just a single wire on it with spade connection. About a tenner from intermotor iirc.

Cheers

thats it

Just took it off - very easy.

The most interesting observation was that it had some whitish/pinkish gunk on it. (See pic) Could be plating-out of the aluminum block - but also could be a symptom of HGF. I've seen a chunk of stuff with the same color floating in the rad and it appears to thinly coat the inside of the cooling jacket.

i would have said original rad was okay.i didnt realise youd already changed it ,as rad is 90% of over heating problems i see leading to hgf.sender looks fine for deposits,i wiuld try changing sender and the run straight wire from sender to rear of gauge to rule out short on the gauge there will be 2 x wires when removed the one with live feed needs putting back and by pass otherto sender as gauge is earthed thru sender

Anyone used (or heard of) these combustion leak testers? Supposedly used for checking head gasket for leaks.

Tool Professional - Shop and Save!

Found a couple videos online of folks using them...

kavefish said:

Anyone used (or heard of) these combustion leak testers? Supposedly used for checking head gasket for leaks.

Tool Professional - Shop and Save!

Found a couple videos online of folks using them...

Click to expand...

Hiya mate, I wouldn't waste your money on that cos the 3.5 V8's are a swine for headgaskets,most of them don't have usual symptoms unless you've properly cooked it(White smoke from exhaust,water in oil and so on)
when you say it's getting hot how hot do you mean? The reason I ask is cos at normal running temp you'll be lucky to hold the top hose for more than 10 secs without loosing some skin. The thermostat is designed to stay closed until about 88 degrees so when it opens the top hose will be red hot(88 degrees) the water goes into the rad,air flowing through cools the water and it goes back in the engine via the bottom hose,so the top will be hotter than the bottom.
When mine gets too hot it starts to misfire and you can hear the water in the top hose thumping and hissing as it boils.
They are really hard to diagnose sometimes and you just have to bite the bullet and do the head gaskets which 90% of the time cure it. If you can get someone to help you do it it's not an expensive job the gasket kit at the most will cost you about £32 and it is only a steady days work

have a look on here,really good site and cheap

Head Gasket Set - V8 3.5 Litre '76 on - Tin at www.rimmerbros.co.uk

cheers Jon - I think there's a head gasket replacement in my future. Would love to do it myself, but don't have a buddy close enough. Still, when I take it into the garage, I think I'll camp out there for the day to watch (if he'll let me).

Shame your so far from me, I'd gladly come and do it for you(for a few beer tokens of course) hope you get it sorted.