Hey guys! I know there are a number of engine knock threads, but I didn't see anything getting to this one....

So I've had an engine knock for a little over 2 months now. This weekend, I went on a fairly long trip (for my 2004 Discovery II SE, at least) to the mountains. At one point, I noticed I was cruising at around 85 mph or so (generally cruise just under 70). In any event, since I got home from that trip, the engine knock has disappeared. I always joke with friends telling me to replace my Rover that it is "self-repairing" b/c the check engine light eventually gets tired of notifying me of issues...but this one was interesting.

Other:
Oil: 5W30 (Synthetic, don't recall brand)
160,000 miles
A couple times, AC has blown VERY hot air...but turn the car on and off and it's back to good (again, self-repairing)
Having some odd, but I think unrelated, issues starting car. Sometimes start seems to really struggle to pull power (alternator good and new battery).

Thanks for your thoughts!

 

How many miles are on the vehicle? What all has been done to the truck regarding maintenance/repair/replacement of cooling system components? (Radiator, hose, hose-assemblies, fan clutch, gaskets, etc.) Are you monitoring coolant/engine temp with a secondary gauge equivalent to hard numbers in real time? (Something other than dash cluster). 5w30 synthetic is a poor choice of motor oil and operating temps over 200f for prolonged periods of time is detrimental to the integrity of this engine. The truck isn't so much self-repairing, more like mind-F*%#ing you. The A/C blowing hot has a direct coorelation with the cooling system of the engine via the heater matrix. Please provide us with answers to the above questions. Also, remove spark plugs individually and photograph each one, documenting its number, appearance, & condition. You are looking for 1 or more that appears much cleaner than the others. Are you losing any coolant, either internally or externally? Do you have to add coolant regularly and what is the level in the overflow tank at the moment?

 

Yeah, basically x2 on that. More info is needed. It's not self-repairing, it's just giving you some signs it is not healthy. Better to figure out what is going on now than pay for it big time later. Definitely need to find out what temps it is running at. Would you say that is more of a tick or a knock? Present at all RPMs?

 

Thanks, guys!

First, I definitely know it is not self-repairing. I'm a weekend warrior on these things but only do things I can learn in here! So, no real skills whatsoever, but enough to know it's not self-repairing ;-)

On the oil...I read 5W30 in here somewhere, but it seems like there are any number of opinions. I'll switch to whatever you guys recommend given your history here - I really have no clue what to go with. What do you guys recommend?

Answers to a small handful of questions, but I obviously have some serious homework to do before I get back to the rest:

- 160K miles on the vehicle
- Head Gasket repair at around 100Kish
- New radiator within the last few months; several new hoses related to the radiator
- New oil pump at around 100K
- Not running a secondary gauge for coolant temp, but based on threads I read in here recently, have pinged a local land rover guy about installing one.
- Losing no coolant at all - completely steady (for once...its had normal discovery issues over the years, but has been good since the radiator repair)
- the hot AC only occurred once and reversed to normal after restarting the car (and has been good ever since)
- I will pull the spark plugs this weekend and report back
- the knock previous was loud, but I would say more of a tick- but a loud one. For a long time, only present at idle and low RPMs and then a bit higher (but couldn't tell after that, just due to competing engine noises)

Still no knock as of this a.m.! Thanks for all of your help!

 

Most of us run shell rotella t4 15w-40. I know it's made for Diesel engines but works great in tappet engines and will help with some of that noise. As for the plugs, a lot use and swear by different ones. I use either ngk platinum or champion platinum. I don't use the +4 or anything like that. I personally run kingsborne wires and the high heat spark boot covers(snake oil but that's just me)

 

An engine knock, ANY engine knock is not a good thing for certain; it should be tended to, or you are risking considerably more engine damage and expense to make it right again. Ignoring a true engine knock, especially taking such vehicle on a long trip, high speeds, high engine rpms, are all pushing your luck, and if nothing major happens soon, it will eventually, usually resulting in major engine damage. Of course some engine knocks are far worse than other ones, and all owners should know how to identify which ones are which, to avoid the major damage/expense to make it right again. Main bearing thump, or knock is really bad, which will soon lead to a damaged crankshaft; possibly worse, if not tended to ASAP. Connecting rod knock is also bad; the damage being quickly accelerated, as the knocking is beating the hell out of your rod bearings, leading to severe damage to the crankshaft, to the connecting rods, with increasing possibilities of breaking a rod, which could likely ram it through the engine block. Valve train ticking or knocking is less serious, but if bad enough can cause all sorts of serious damage, such as broken valve push rods, broken rocker shafts, broken rocker arms, etc. any of which could cause serious damage to heads.
All Rover, and similar engines, using similar valve train, need Shell Rotella 15W40, designed for diesel engines, or better yet 50, for the valve train, which properly lubricates that valve train, making it run much quieter. Other, non diesel modern oils, especially ones of lower viscosity, will not lubricate this older style valve train properly, so they will make the vulnerable valve train susceptible to more wear over time, and resulting in more valve train noise, a loud to heavy tick tick, tick, or worse.

 

No worries, everyone has to start somewhere!

A lot of people on here use Rotella 15w40. I like it, engine runs good in the warm weather with it.

You don't need to have one "installed", you can just use an OBDII port with a scanner. Scanguage and Ultraguage or something like them are a must have. My Ultraguage has saved me more than once.

If the tick does does come back, which it will, try to get a video of it. Try to see if the tick goes away above 3,000 RPM. Or see if it is only present once the engine warms up.

I'd pull the plugs and see. Switching to Rotella with a good new filter could fix it.

 

Thank you all so much - I'm going to give all of this a shot this weekend and grab some video/ audio of the knock. Hoping it's a tick....