Tekforums
Chat => Sports, Hobbies & Motors => Topic started by: El Jacko on July 20, 2008, 11:13:28 AM
-
Seeing as this isnt getting very far in the Waffle thread, I thought Id start one over here. Anyways, the engine in question is a Rover V8 3.5l, slightly old and corroded [its been running on saltwater cooling for a while now, its the engine in a jetboat]. Every year weve used it its taken a bit of tinkering, but has always started. This year though, nothing. The timing is corrrect [we set to what it says in the manual], the firing order is just so, all of the spark plugs are firing just after top dead centre, theres oil, fuel and valves opening when they should and it wont even cough. We would, if we could, just crank the engine on the starter motor until it fires, but the main bearing in the jet is on its way out.It was replaced a few years ago, but the screws holding the jet together had corroded away, so we had to weld the unit shut. I just need to know a quick fix that should get it fired up and hopefully get another year or two out of it.
The engine has been slightly modified by way of installing a four-chamber Holley racing carb and semi-racing cams. The jet unit is a Hamilton 2-stage flow jet from NZ.
edit: four of the valves werent doing quite what they should
-
have you checked the compression on the cylinders?
-
take all the plugs out, pour a teaspoon of petrol down into each cilinder, put the plugs back in and try it again ;-)
-
Is the fuel getting into the cylinders?
Is the air getting in OK?
obviously a petrol internal combustion engine needs air, fuel, compression and a spark to fire, so if its sparking and the air filter isnt blocked and fuel is getting in, then Id suspect the compression is out.
-
take all the plugs out, pour a teaspoon of petrol down into each cilinder, put the plugs back in and try it again ;-)
Tried that, it wouldnt cough so we held a match to the exhaust and had a 4ft flame shoot out of it
And as for Chris, 1) yes 2) yes
It could be the compression, but weve no way to find out. I think what were going to try is to remove the driveshaft and just keep cranking it for as long as the battery will let us or until we get it to cough. If that fails, well have to consider finding a way of sorting out the compression. As this boat is going to be with me on holiday, I wont have internet so ideas on fixing the compression will be much appreciated.
-
Id re-check its sparking in the right order... you could always have it set so its sparking on the exhaust stroke instead of the compression stroke....
(this only really applies if youve had all the plugs out/disconected at the same time since last time it worked...)
plus id take out the prop shaft, then take a generator and a good battery charger with me ;)
-
Well, weve set the timing so it fires just after top dead centre [as is said in the manual], all vales closed, after the intake stroke. The valve timing is just so: we can hold a match to the exhaust while cranking and light the unburnt the petrol. Its just not firing. The spark plug are [i think] sparking properly, Id have to check that tho. But cant til saturday.
-
if you can light the exhaust then Id say its defenatly a spark problem... even with next to zero compresion, the fuel should still be ignited...
Id re check for a spark, and re-check all the daft things, like you havent leaned on and pulled out the coil power etc... :-o
-
righty ho then
As always, keep the ideas coming for any possible faults and fixes. Ill take a list with me to try.
-
if its cranking and not firing but is sparking
are you getting a good spark?
check compression as above
what state is the carb in? When was the last time it was serviced
are the cams degreed to manufacturer spec - NOT oem spec
Is the starter good? If it wont turn fast enough it will never build enough compression to start
how old is the fuel?
-
1) dunno need to ckeck
2)will do
3)pretty good nick, didnt need servicing the last time we got someone qualified to look at it
4)no idea
5)probably not. Weve got a new one to try anyway.
6)god knows. Probably 12 months old. Used to be unleaded, we put enough additive in it to boost it to 5-star racing-quality
-
Right then, seeing as Im back off holiday, I might post the state of thise here engine.
First, we took the simple approach and attempted to remove the drive shaft from the flywheel and crank the engine til it coughs. We gave up on that approach when we snapped the only allen key that would fit [the end of it is still in the bolt]
Secondly, the rocker covers came off. The contents of said covers were...dodgy at best. The rockers themselves were corroded, and four had siezed. With a little tlc however, they were good as new.
Then we saw the state of what was underneath the rockers. Four of the cams had seized, and those four cams had caused their respective pushrods to bend into a z-shape.
So, after seeing the state of the heads we decidied they needed reconditioning. Hence the holley carb [still pristine], the offenhauser inlet manifold and both huge Nicson water-cooled exhaust manifolds had to come off. The first two came off all right, but the steel pins holding the nicsons on had corroded into the aluminium of the manifolds and block, effectively welding them together. Much levering and the aid of a large hammer solved that problem. Once the heads came off, we saw the state of the block [the 7th and 8th cylinders looked deceptively dodgy, but the gunk in em was just from last years backwash, the block was almost perfect underneath]. So, the heads have been sent off to be re-conditioned and the engine should be running by the end of the season. I will post pictures as soon as I can get then off my phone [lost the transfer cable, wont have a card reader til mid-week].
-
a compression test at the start may have avoided all the damage :/
-
thats what you get for using a petrol engine in a boat :p
-
A compression test may have helped, but the first turn of the key this season knackered the pushrods. I think 17 years of rot took its toll slightly....and as for Knighty, a petrol engine was the best choice. A diesel engine wont chuck out all its torque and power at 5500 revs and last more than a season.
-
Im just winding you up :p
I used to do a lot of work on my brothers boat when I was a kid... well i did until he jabbed me in the face with a minging mop and pushed me over the side..... the river wear doesnt taste so good :(
-
the river wear doesnt taste so good :(
Ive heard it tastes a bit like Newcastle Broon does now they make it in Gateshead.
-
Ive never waterskied in a river. But I have kneeboarded in a river. At high tide. In 3 inches of water. Sideways :w00t:
-
use the opportunity to buy a modern V8 - the half buick 3.5 rover is a bit of a 1960s relic.
An LS1 can be had for fairly handy money these days
-
We havent got any plans to spend real amounts of money on it. We decided that if it needed a whole new engine it was only worth scrapping, the rest of the boat is almost totally worthless.
-
OK, pictures time. I admit theyre a bit big, but I dont have the time nor the attention span to shrink em.
The first is the shape of the pushrods, one good one bad, the second a snap of the backwash rot and the third is a picture of the stripped block
-
And heres a snap of 1) the rockers and 2) the almost intact engine
-
OK new update, after totally dismantling what was left of the heads we found it was cheaper and quicker to scavenge some new ones.
-
Looks like it would be cheaper to scavange a new engine, Im sure knighty has something suitable in one of his trucks you can nick ;)
-
:stupid:
-
Looks like it would be cheaper to scavenge a new engine, Im sure knighty has something suitable in one of his trucks you can nick ;)
oddly enough Ive got a boat engine in the yard at work.... 11 litres of diesel goodness !
(soon to be part of a combined heat and power system!)
-
You should put the 21l Merlin engine in a boat
-
Where are we going to get a 21000cc merlin V12 from with a budget of under £200?
-
EBAY !!!!!!
-
Is that a half V8 ? In that case it must be a lot of good fours around like a volvo B18 engine which also comes as marin engines a reliable engine it is.
-
er...its a rover V8, i.e. 8 cylinders [well, 5 1/2 three weeks ago, back up to 8 now]
-
er...its a rover V8, i.e. 8 cylinders [well, 5 1/2 three weeks ago, back up to 8 now]
this http://www.autorevue.cz/Obrazky/2006/03brezen/volvop1800/P1800motor.jpg
ok V8 and it is the aluminum block ? har to find other with that low weight unless a modern 6 cyl diesel ?
-
Wed rather stick to this beast. The block is light enough to be lifted out of the boat by 2 blokes, and it still gives in excess of 150bhp at 5500revs
-
I guess the old adage "if it aint broke dont fix it" applies here
altho it was broke........so u did fix it.....maybe that doesnt apply then :/
-
Well, it wasnt entirely broke, so we roughly followed the old rule.
-
Right then. My uncle, who sourced the new heads, has today fitted them to the engine, put it back together and hey presto - ignition! After 17 years of punishment the old girl still runs. So a happy ending ensues.
-
er...its a rover V8, i.e. 8 cylinders [well, 5 1/2 three weeks ago, back up to 8 now]
Strictly speaking, its a Buick V8 that rover bought the rights to.
-
And it came from a Rover P6 [also known as the Rover 3500]
-
For all the comments of "Buy a more modern engine" most modern engines dont take the same level of punishment that those old V8s can. Ive seen them used in loads of boats over the years purely because they are such old tech that not much can go wrong. Perkins used to take the V8 block and build marine engines round it even. They are old, clunk and near impossible to kill.
-
This one was a semi racing engine from a company that specialised in tuning engine for racing. For the £2000 it cost originally weve gotton a lot out of it. It could pull 3 skiers from a deep start when it was new.
-
For all the comments of "Buy a more modern engine" most modern engines dont take the same level of punishment that those old V8s can. Ive seen them used in loads of boats over the years purely because they are such old tech that not much can go wrong. Perkins used to take the V8 block and build marine engines round it even. They are old, clunk and near impossible to kill.
A modern 1.0 litre japanese engine would run flat out for maybe 10 times longer.
-
A modern 1.0 litre japanese engine would run flat out for maybe 10 times longer.
Provided you actually maintained it 100% correctly, and didnt let it get into hostile conditions like the V8 has had. Ive spent loads of time around marine engines over the years, they where my introduction to mechanics to be fair. The older V8s and the like are loved because they are lazy revving, and they take way more punishment than the more modern small engines.
-
A modern 1.0 litre japanese engine would run flat out for maybe 10 times longer.
A modern 1 litre jap engine wouldnt give 200ft/lbs of torque
-
Anyone who has been watching Top Gear recently would know how much engines have improved over the last decade. A more modern lump would provlde more power and be more economic to run.
Obiously the older one would have less problems with reliability, which is why older cars have longer warranties and didnt keep breaking down :roll:
-
Anyone who has been watching Top Gear recently would know how much engines have improved over the last decade. A more modern lump would provlde more power and be more economic to run.
Obiously the older one would have less problems with reliability, which is why older cars have longer warranties and didnt keep breaking down :roll:
Difference is that those V8 lumps can pretty much have the pistons slapping around the bore, and they still fire. One of the favs in boat yards with older boats was the old Rover 2.5D. They stink, they are noisy, but they keep on running no matter what you do. On the other hand more modern engines are made with far more precision, but as a result they require far more looking after and maintenance.
-
For 17 years of rot going through it, until now the only thing this boats needed to start is a change of oil and a brief cleaning of the spark plugs, sometime a new starter and oil filter. The starter motors have had more problems than the engine, weve currently got 3 on a cycle of use - fix - store - use again. A modern engine would need yearly if not quarterly maintenance.
-
And you think that one shouldnt be serviced yearly? :shock:
Modern ones are just as capable of taking abuse without problems, if not more so.
-
Hows about we close an argument Im bound to lose and discuss more pressing matters, such as: does anyone know how to unstick some epoxy resin?
Anyways, keep in mind my old mantra: If it aint broke dont fix it.
-
http://www.westsystem.com/frames/tier1/usingepoxy.htm
Seems you need to heat it a bit - 200C
-
Modern ones are just as capable of taking abuse without problems, if not more so.
no they arent, not in a boat they arent. in a car where they are relatively protected they are fine, but in boat where they are actually living in hostile conditions they fail hard. Modern engines just tend to electrical fault for fun, because the ECU etc just get fried due to how wet they get. The smaller 2-stroke outboards are maintenance heavy regardless of what you do (I always liked the Yamaha 4 strokes due to more control and less hard work), but for an inboard motor you want something easier to fix, that doesnt rely on having to be taken into a workshop to fix it.
-
I think seeing as no1 here actually has a modern engine in a boat then its all speculative
whereas El Jacko does have an old engine in a boat and finally did break after years of abuse we can safely say that they do take a lot of punishment
-
And hopefully now we can subject it to a few more years of abuse